Jay Leno, as affably efficient backstage as he is in front of the camera, avoids waxing poetic about his 22-year Tonight Show run that draws to a close Thursday.

Instead, he relies on numbers to tell the story. Leno's tenure is second only to Johnny Carson's 30 years; Tonight was No. 1 among viewers when he took it over and will be when he hands it off to Jimmy Fallon; he'll have taped more shows than any predecessor, Carson included, with the final and 4,610th one.

His dry assessment also may stem from a case of déjà vu. After all, he lived through this before when he surrendered Tonight in 2009 to Conan O'Brien, only to reclaim it after NBC's messy bobbling of the transition and O'Brien's lackluster ratings.

'It's been a wonderful job but this is the right time to leave' - Jay Leno

But this time it's different, Leno contends, offering another hard fact: The older generation has to make way for the younger one.

Queen Elizabeth II can keep 65-year-old Prince Charles cooling his heels. Leno doesn't have the power to do the same with Fallon, 39. The Late Night host is moving the show from its longtime Burbank home, near Johnny Carson Park and off Bob Hope Drive, to its New York birthplace when he debuts as host on Feb. 17.

"It's been a wonderful job but this is the right time to leave," said Leno, whose once-dark mop of hair is now a neatly groomed silver. "I'm at that age where I don't really listen to the [current] music anymore. I'm not a big tweet guy. A 63-year-old guy reading Miley Cyrus' tweets is a little creepy. Move on."

He makes the argument with the precision of one of his reliable monologue jokes, just as he did when he claimed to understand NBC's decision to evict him for O'Brien — even as he reamed the network on the air.

The years between then and now have seen changes come at a quickening pace, with an ever-more crowded late-night arena and a shifting media environment. Fallon's parody music bits with contemporaries like Justin Timberlake are perfect cut-and-pastes for sites like YouTube that drive young viewer attention and offer new potential for ad sales as network revenues shrink.

In 2012, Tonight laid off 20 staffers and Leno took a 10 percent pay cut. The show has averaged a 3.5 million nightly viewership in the past 12 months, which pales in comparison with the double-digit audiences it once claimed.

Future plans

Leno is planning to expand the comedy club gigs he never abandoned and various outlets for his automotive passion, including the Web show Jay Leno's Garage, and the magazine and newspaper pieces he writes. He insists his schedule won't include another late-night show, which could only be what he calls Tonight Light.

"It's hard to re-create this moment. It's like the fighter coming back. You got to be world champion, so it's kind of silly," he said.

Tonight, which launched in 1954, was shaped by original host Steve Allen and nurtured by successors Jack Paar and Carson. Following them represented the pinnacle for comedians, and it was the role Leno coveted and won upon Carson's 1992 retirement.

His first few months were marred by Leno's longtime manager Helen Kushnick, who, as his first Tonight executive producer, was blamed for instigating nasty guest booking wars and fired in what then was characterized as one of TV's biggest publicity nightmares.

'There's nothing to be sad about. He's had a tremendous career' - David Letterman on Jay Leno

Worse was to come, when NBC's Tonight host succession plan hatched in 2004 went awry. Leno, who stoically endured insults from Jimmy Kimmel and others who portrayed him as having stolen O'Brien's job, says the past is past. CBS' Letterman, who once jockeyed with Leno for Carson's throne, echoed that.

"How long can I carry this with me?" he told Howard Stern during a SiriusXM interview Friday. He spoke of calling Leno when his second Tonight departure was announced, their first conversation in several years, and tipped his hat to his rival when Stern asked if Leno sounded sad.

"I wouldn't say sad. There's nothing to be sad about. He's had a tremendous career there," Letterman said, graciously.

Jay Leno's top targets

For Jay Leno, Bill Clinton was the comic gift who kept giving. By one exhaustive count, the outgoing Tonight show host made 4,607 jokes at the former president's expense during his time on the program.

The Center for Media and Public Affairs catalogued nearly 44,000 jokes Leno made about political figures and celebrities at Tonight through Jan. 24.

His first Clinton joke came on May 25, 1992, shortly after taking over from Johnny Carson and when Clinton was still a presidential candidate.

"Clinton says that he's troubled by the amount of sex on television," Leno said. "He says that where he's from sex is a deeply personal thing between a candidate and his campaign volunteers."

Clinton was subject of more than a thousand jokes ahead of the runner-up, George W. Bush. His top 10 targets for jokes were:

  1. Bill Clinton: 4,607 jokes.
  2. George W. Bush:3,239 jokes.
  3. Al Gore: 1,026 jokes.
  4. Barack Obama: 1,011 jokes.
  5. Hillary Clinton: 939 jokes.
  6. O.J. Simpson: 795 jokes.
  7. Dick Cheney: 673 jokes.
  8. Michael Jackson: 505 jokes.
  9. Monica Lewinsky: 454 jokes.
  10. Bob Dole: 452 jokes.

Others have chimed in. Politically Incorrect and Real Time host Bill Maher, a regular Tonight guest, and Seth MacFarlane (Family Guy, Ted) serenaded Leno last week to the tune of Thanks for the Memories. It was reminiscent of Bette Midler's saucy You Made Me Watch You tribute to Carson. This parody was edgier.

"You've been retired and twice been fired for being No. 1. How stupid they are," the pair sang, zinging NBC as a surprised, bemused Leno watched.

Maher was expansive when asked to comment on Leno.

"As a performer trying to make it in show business, and as a human being, you cannot do better than ask, `What would Jay do?"' Maher said in an email Saturday.

Final guests

Leno's final show will feature Billy Crystal, his first Tonight guest, and Garth Brooks. Leno's legacy — a word that makes him squirm — might include expanding the show's opening monologue; a memorable mea culpa from Hugh Grant after he was arrested in 1995 with a prostitute; the first interview with a sitting president, Barack Obama, in 2009; and the "Jaywalking" fixture, which trips up people with simple questions.

Leno's favourite Q&A is that those queried about how Mount Rushmore was formed often reply, "erosion." His head-shaking reaction: "The wind and rain not only picked four presidents, it picked four of our greatest presidents!"

Was he the most daring, most innovative, most surprising force in late-night? His critics and even clear-eyed admirers said no, and Leno doesn't argue with them — but that's not what counts, he adds: "Whether you like the host or not, you cannot say it's not been a success. A football team might not have the most sophisticated players but can win the Super Bowl."

Leno cannot be called unsophisticated but he is determinedly un-show biz. He makes note of his modest New England upbringing, the high school friends he remains close to, his three-decade marriage to wife, Mavis, and the many Tonight staffers who remained loyal throughout his tenure.

Hollywood has been a place to get to tell jokes to a big audience, reap millions of dollars to be carefully saved and keep a safe distance from the circus.

"When this is over, I don't get to my table at [posh restaurant] Morton's and" — here, he feigns dismay as he mimics a maître d' — `Sorry, Mr. Leno, this is Mr. Fallon's table."'

Instead, the day after Leno steps off the Tonight stage, the one designed for him, he will travel to Florida for a handful of club dates, his wife at his side. And, he said, he'll be content with that.