Roughly 59% of Internet users use the latest, more secure Web browsers, according to an examination of what version Web browser, down to the patch level, people are using. That means about 576 million Web surfers leave themselves vulnerable to attack. You might just (not) be surprised by who doesn't patch.

The study, published today, was conducted by the Swiss Federal Institute of Technology, Google, and IBM Internet Security Systems. The researchers found that no matter how quickly browser and plug-in vendors create patches to fill security holes, it could be months before a large segment of the Internet population will apply those patches.

While I wasn't surprised to see 83.3% of Firefox users having applied the most recent patches, the same can't be said for Opera users, because only 56.1% of those users keep their browser up to date. One would think that both Firefox and Opera users would be more technically savvy than the average user, thereby more prone to patch. Unlike Internet Explorer users, where less than half, at 47.6%, bother to apply the most recent software updates.

The study examined search and Web application log data from Google to ascertain what version of browsers, including patch levels, are used. For Internet Explorer, the researchers culled data from Danish security firm Secunia's Personal Software Inspector.