The average female Facebook user uploads a new profile photo to her account every two weeks.

Men typically update their profile photo less often on the social networking site, averaging one new profile image every three weeks, deduced photo discovery and image managing service Pixable after analyzing the profile pictures of its more than 500,000 users.

Over the years Facebook users, both male and female, have started changing their profile pictures more often. Since 2006 the number of profile photos poster per user per year has tripled.

"Perhaps, we recognize that having an online presence is now the norm and maintaining it is important," said Pixable in a May 27 blog post attempting to explain why users are uploading more profile pictures every year.

"The internet after all has become an integral part of many of our lives, and Facebook is only becoming a more primary channel of communication - a channel that ties every message to an online representation of ourselves (our profile page)."

The magic number for Facebook profile picture uploads is 18 times per year in 2011, up from 6 at the beginning of 2006 and just under 12 at the beginning of 2009.

Another reason Facebook users might be uploading new profile pictures so frequently is to gain extra attention from their friends and family.

According to Pixable, the typical profile photo has three likes and two comments.

If you're thinking of uploading a new profile photo and want to gain the attention of your Facebook friends, you should stay away from landscapes.

A study published on May 24 by neuroscientists at MIT found that the most memorable photos were those that contained images of people while landscapes were "in most cases, utterly forgettable."

Facebook is expected to reach the milestone of 100 billion uploaded photos this summer, around 10 percent of which are profile pictures.