FORTUNE — Tim Cook likes to cite NetApplications‘ monthly usage reports to show that no matter how much ground they lose to Google’s (GOOG) Android in terms of unit sales, Apple’s (AAPL) mobile devices continue to dominate the Web.
It will be curious to see if Cook cites the Web analytics firm’s stats at Apple’s next special event, because according to NetApplications’ latest report, August was a particularly bad month for iOS.
According to survey results released Sunday, iOS’ share of Web usage hit an all-time low of 54.9% in August, down 11 percentage points (16.7%) from the 65.9% it held in August 2012.
Android, meanwhile, surged to 28.1% from 21% last year, up 7.2 points (34.3%).
Apple’s units sales should rebound if, as widely reported, the company is set to release new iPhones in September. Its Web share may take longer to recover.