The WSJ is highlighting some concerning data from comScore in regards to Facebook users, and it could put the pressure on shares of the recently-gone-public social site.

Research firm comScore says the user growth of the world’s largest social networking site has started showing a sharp decline. As per report, in April, unique visitors in U.S. to the website jumped to 158 million, up just five percent year over year. This growth rate is the slowest increase at least in the past four years. In April of the last year, the website had witnessed a 24 percent growth and 89 percent in April 2010.

To be fair, Facebook has already grabbed 71 percent of all 221 million U.S. Internet users, according to comScore, so a slow down isn’t too surprising.  

Users already spent most of their time on Facebook, too. comScore said the more than six hours a month that people spend on the social network exceeds the over four hours a month they spend on all Google sites including YouTube.

Of course, despite the fact that Facebook has 71 percent of Internet users, the site held a vote on whether it should change its privacy policy (again) and the amount of users that voted was underwhelming.

According to a report, at the time of the launch of the voting, in order for the vote to make any sort of a difference, 30 percent of the site’s total users must log a vote in order for it to be determinative.

342,632 votes were cast – not even close to the 270 million needed. As a result of the low turnout, Facebook will be using the vote in an advisory manner to consider the changes to its new policies.

What was being voted on was the usual suspect of Facebook’s ever-changing privacy policy: how transparent the information actually is and how they share info on their users.

The lack of transparency in collected information, how long it's kept, whom the company shares the data with, and making some data collection opt-in and not opt-out was the highlight.

According to Ars Technica, Facebook didn't make users aware of voting outside of the Site Governance Page which has two million likes.

"Perhaps they knew that getting 270 million people to participate in anything, especially something as dry as a vote on a privacy policy change, would be a pipe dream," Ars Technica said