Firefox's U.S. market share across all operating systems reached 5.69 percent as of February 18, 2005, an increase of 0.74 percent in share since January 14. After gaining 1.03 percentage points of market share from November to December, adoption of the new Mozilla browser cooled slightly to a 0.89 percent increase from December to January. It slowed further between January and February.
Microsoft's Internet Explorer, meanwhile, now commands an 89.95 percent share of the market, a decline of 0.43 percent from the preceding month.
''This has been an ongoing story,'' said Jeff Johnston, a WebSideStory analyst. ''We first discovered that Microsoft was losing share last June, which had never happened before. Now, it's been going on for eight or nine consecutive months. The current numbers reveal steady growth for Firefox, primarily at the expense of Internet Explorer.''
WebSideStory's findings were based on an aggregate study of the more than 30 million daily unique visitors to the 700 enterprise businesses and thousands of small businesses using its analytics tools.
''The question since the launch of Firefox's 1.0 browser in November, has been, When will it taper off?'' Johnston said. ''Well, the current numbers show that if you thought Firefox was going to keep growing at a percentage point a month, you were wrong. The good news for Firefox is it is still growing at over a half point per month, which is faster than it was before November.''