What percentage of Mac users have OSX Lion or higher? I'm working on a web app and the user needs Safari 6.0 or higher which means they need Mac OSX Lion or higher (per Wikipedia)

Users can install Chrome in that case, but I'm wondering how much of an "edge case" this is.
According to Chitika, in North America, 55% of Macs on the Internet are running Lion or later. Source: Gotta Be Mobile