Xiti Monitor, a European company, has measured Firefox usage on a recent Sunday. The figures are really impressive, ranging from 8.6% in Italy (lowest number) to 21,4% in Germany:

  1. Germany: 21,4%
  2. France: 12,2%
  3. UK: 10,9%
  4. Spain: 9,0%
  5. Italy: 8,6%

Firefox usage on Sunday 2005-03-06 in five European countries

(Source: Xiti Monitor)

For more details, read the Story in French. As Xiti states,

We should emphasize that these measures have been done on a Sunday, when Firefox' usage peaks. The Firefox browser is less used during the week, as Enterprises are more conservative when it comes to using a newer browser.

So don't go claiming that Firefox has more than 20% market share in Europe, that would be just plain wrong. However, it is to be noted that Web sites aiming at the consumer have not other choice but making sure that they are compatible with Firefox in order to reach their full potential. Ignoring compatibility with Firefox and other modern browsers does not make sense business-wise.