The following breakdowns of non-mobile and mobile traffic are based on our squid logs.
Note how share of mobile usage peaks every year around Christmas.
Note how mobile here is to be taken as ‘traffic from mobile devices’ not as ‘traffic to our mobile site’.
See also the Wikipedia article on usage share by browser.
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Wikipedia and sister projects.
The most recent data is unusual, too. c. February 2012, there’s a sharp increase in mobile Safari and Android, a moderate uptick for non-mobile Chrome (which might just be unusually large normal growth), mostly at the expense of IE and, to a lesser extent, Firefox. There wasn’t a similar mobile spike after Christmas in 2010 or 2011, so this doesn’t seem to be seasonal.
I originally wondered if it was from the Android app released a month ago, but presumably that wouldn’t increase Safari usage…