"IE8 continues to lead in user choice," Gavin argued. "It grew 2.5 times faster than any competitor." He arrived at the two-and-a-half times figure by comparing IE8's global increase of 0.81 of a percentage point with Chrome's growth of 0.32 of a percentage point.
IE8 closed May with 35.38% of the U.S. browser usage share, making it the most-used browser in the country. Microsoft's IE7 was second, with 16.75%, said Vizzaccaro, while Mozilla's Firefox 3.6 was third with 13%. Google's best showing was at No. 8, where Chrome 4.1 accounted for 3.52%. Chrome 5.0 , which just shifted out of beta into what Google dubs its "stable channel," owned 0.76% of the usage market.
"Microsoft is doing extremely well with IE8 in the U.S.," said Vizzaccaro in an e-mail today.
" Windows 7 [growth] is certainly part of the reason why IE8 is growing," said Gavin, when asked for Microsoft's explanation of IE's increase in the U.S. "But there is more choice in [the browser] space than at any other time in history," he said, adding that when IE8 goes head-to-head with rivals, such as in Europe, where Windows users have been offered a government-mandated way to change browsers, IE8 does well.
"IE8 grew half a percentage point in Europe last month," said Gavin, to 29.69%.
Besides touting the climb of IE8, Gavin also plugged the success that Microsoft has had in driving down the share of the nearly-nine-year-old IE6, the aged browser that Microsoft has been aggressively urging customers to ditch. He confirmed that one of his tasks is to push IE6's share to zero.
"In the U.S., we're seeing that tip-over [towards zero]," Gavin said, and again credited Windows 7 and IE8 adoption as reasons. Windows 7, the operating system Microsoft launched last October, was the first to include IE8.
Microsoft has made more headway in its "kill IE6" movement in the U.S. than it has globally. According to Net Applications, IE6 accounted for 6.74% of all browsers used last month in the U.S., a number substantially lower than IE6's worldwide average of 17.13%.
The two biggest groups of customers still running IE6, said Gavin, are enterprises having trouble migrating because of mission-critical Web applications or sites that rely on the old browser, and users in emerging and underdeveloped markets. There, the global economic recession and sluggish recovery have stalled efforts to upgrade from Windows XP to Windows 7.