As noted by Macworld UK, Apple's Mountain Lion has clawed its way to the top of the Mac OS jungle
From TUAW:
It was released on July 25, 2012 and as of this past December accounts for 32 percent of all Macs online, according to Net Applications, a web-measurement film that tracks OS usage by visitors to 40,000 websites.Mountain Lion is king of the OS X jungle
That 32 percent represents a 3 percent increase for the OS from November when it accounted for 29 percent of all Macs online. That gain came mostly from OS X 10.7 Lion, which sank from 30 percent to 28 percent. Mountain Lion also stole one percentage point from OS X 10.6 Snow Leopard, which is now actually in second place, accounting for 29 percent of all Macs.
