The number of Canadians logging on to their Facebook accounts fell in May, a website that covers the social network said Monday.

A report on Inside Facebook said that the number of Canadian Facebook users fell by 1.52 million to 16.6 million during the month. The site defines a user as a "monthly active user" — someone who logs on to their account at least once a month.

Inside Facebook caters to the advertising and marketing industries by tracking Facebook's growth data, demographics and usage statistics.

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The drop in Canada is in keeping with a global trend at Facebook where its growth is starting to slow in developed economies where it is entrenched.

"By the time Facebook reaches around 50 per cent of the total population in a given country … growth generally slows to a halt, as we’ve noted before," the website reported Monday.

687 million users

All in all, Facebook had 687 million monthly active users in May, an 11.8-million increase over April's level. That month, Facebook's reach expanded by 13.9 million users.

The last 12 months have seen average monthly gains of about 20 million. Two comparatively weak months in a row could be a sign of a slowdown for the world's largest social media website.

The U.S. is still Facebook's largest market. But use there fell by six million users to 149.4 million in May.

Worldwide, Brazil was among the fastest growing markets for Facebook, where the number of users grew from 17.1 million to 19 million during the month. Countries such as Mexico, Indonesia, Philippines, Colombia and India were all among Facebook's fastest-growing markets for the month.