From March 2011 until June 2012, Firefox lost 7.5 percentage points of share in Europe, according to data from Irish metrics company StatCounter, an average monthly decline of nearly half a point. In the 16 months prior, Firefox lost just 2.3 percentage points, an average of 0.14 point.
In the three months since Microsoft reinstituted the ballot, Firefox's average slip has been three-tenths of a point, a 40% reduction from the 16 months when the choice screen was AWOL.
Other factors beside the missing ballot, however, clearly played a role in Firefox's decline, including the concurrent rise in Google's Chrome. During the March 2011 to June 2012 span, Chrome, which was also supposed to be on the ballot, grew its share by 13.7 percentage points, slightly more than the 16 months prior.
Nor did the omission of the browser choice screen keep Microsoft's own Internet Explorer (IE) safe from erosion, although its usage decline slowed by 27% during the 16 months when the ballot was not served to Windows 7 users.
While Anderson did not mention it, the vast majority of Mozilla's income comes from a search partnership with Google, which reportedly is worth $300 million annually to the open-source developers. Fewer downloads would likely translate into fewer users -- although not on a one-for-one basis -- which in turn would mean less revenue from those users searching with Google and clicking on its ads.
Microsoft has about three weeks remaining to respond to the Commission's charges, and can request an oral hearing to air its defense before regulators decide on a fine.
But Joaquin Almunia, the EU's head antitrust official, has talked tough ever since July.
"If companies enter into commitments, they must do what they have committed to do or face the consequences," Almunia said last week during a news conference to announce the charges against Microsoft. "Companies should be deterred from any temptation to renege on their promises or even to neglect their duties. This is why, when this happens, the Commission has the power to impose fines."
Almunia also told Microsoft that it had to offer a ballot display in Windows 8, the upgrade that launched Oct. 26, but that it had finished its investigation into similar charges about Windows RT, the tablet-oriented spin-off, and would not force the company to insert a screen there.
Microsoft promised to comply on Windows 8, and last week said it would push an update to the new OS by its Friday launch.
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