As charted by GoSquared based on all the pageviews across all the sites they are tracking analytics for.

Here on — which has a decidedly more Mac-nerdy audience — Mavericks is already the dominant desktop OS, representing 21-percent of today’s total pageviews so far.

Here’s the breakdown for my site so far today:

Operating System Percent of Pageviews
iOS 7 (iPhone + iPad) 33%
Mavericks 21%
Mountain Lion 19%
Windows 7 16%
The Rest 9%
Mavericks Adoption Rate