We’ve heard time and again how time-consuming Facebook can be. Nevertheless, I always find the statistics mind-blowing: Americans spent a total of 53.5 billion minutes on Facebook in May 2011, according to the latest data from Nielsen.

How does this compare to other websites? Well, Americans spent more time on Facebook than on any other website. The competition doesn’t even come close: Yahoo was second with 17.2 billion minutes and Google was third at 12.5 billion minutes.

Let’s do some simple math to figure out how many Facebook minutes are spent, per person. Unfortunately, the company doesn’t release exact numbers for US users, so we’ll have to estimate. Two months ago, Facebook said it had 750 million active users. The social networking giant also says that about 70 percent of its users are outside the US, meaning there are some 225 million US Facebook users.

Nielsen specifically says it counted 140,336,000 Facebook users, however, so we’ll use that number. The calculation thus becomes 53.5 billion minutes divided by 140,336,000 users, divided by the 31 days of the month. Americans spent an average of 12.30 minutes on Facebook every day in May.

Here are some other highlights from the report:

• Social networks and blogs continue to dominate Americans’ time online, now accounting for nearly a quarter of total time spent on the Internet
• Tumblr is an emerging player in social media, nearly tripling its audience from a year ago
• Nearly 40 percent of social media users access social media content from their mobile phone
  Internet users over the age of 55 are driving the growth of social networking through the Mobile Internet
• 70 percent of active online adult social networkers shop online, 12 percent more likely than the average adult Internet user
• Across a sample of 10 global markets, social networks and blogs are the top online destination in each country, accounting for the majority of time spent online and reaching at least 60 percent of active Internet users

If you want more information, check out the 14-page report, titled 011. The data is the most recent from Nielsen: it was released today.