Even Mozilla's Firefox, which has lost share eight out of the last 12 months, managed a slight increase of one-tenth of a point, the first increase since December 2010, to account for 21.8% of all browsers.

The March 22 launch of Firefox 4 contributed to Mozilla's small turn-around. Net Applications' statistics show that Firefox 4 boosted its share to 1.7% last month, a 1.1-point increase over February.

Microsoft and Mozilla have each touted the number of downloads of their newest browsers, but the latter has clearly won that battle, claiming 7.1 million downloads on Firefox 4's first day of availability and a the following day.

Gavin has argued that IE9's numbers should be calculated solely by its use on Vista and Windows 7, and its success or failure judged accordingly.

Net Applications put IE9's share of browsers running on Windows 7 at 3.6%, more than three times the overall average, a fact that Gavin stressed during an interview today. "That's about five times the rate of adoption in a comparable period for IE8," Gavin said.