Privacy concerns don't seem to have scared Canadians off Facebook. Canada passed the 16 million users mark in May, according to research firm Inside Network. More than 912,000 Canadians signed up for the social networking site last month, a six per cent increase in membership Inside Network says an estimated 47.9 per cent of Canadians are on Facebook, making Canadians some of the heaviest users of the site in the world. Overall, Canada is the fourth largest market on Facebook, on a per capita basis, behind Iceland, Norway and Hong Kong. About 59.6 per cent of Iceland's population has a Facebook profile. But among larger countries with at least 10 million citizens, Canada is No. 1. There has been speculation recently that Facebook is approaching 500 million users worldwide, although officially, it has only stated that it has more than 400 million users. Inside Network says Facebook now has about 465 million users in total and might be weeks away from hitting the half-billion mark. Facebook has averaged about 500,000 new users daily for the last year but spiked in May with about 30 million new members, Inside Network says. Facebook does not give specific membership numbers, but Inside Network uses data provided to advertisers to gather insights about the social networking site.