Not statistics, per se. I don'think there are any statistics as to the estimated number of Islamic terrorists per country. It's just that I've read a lot of reports over the past few years about international terrorism and they all point to France being the European country that is best able to handle the problem most efficiently.
I remember one interview with a terrorism expert who said that French Muslims were particularly difficult to recruit into the global Jihad. Which is not to say that they can't be recruited for domestic terrorism. They absolutely can. In fact, when French Muslims join terror groups, more often than not, they are groups primarily focused on targeting France. I wish I could find that interview again, but I haven't been able to. It was quite a while ago, so things may have changed somewhat, although I don't see any evidence of such at this time.
France has got the largest Muslim population in Europe, estimated at over 5 million people. Olivier Roy, a French political sciences and sociology expert who specializes in political Islam, estimates the number of actual Jihadists in France at around 1000. Very few end up on the news in the context of international Jihad. Given the large number of Muslims in France, their social difficulties in a country that still treats them as outsiders and the general anti-muslim momentum in the West, you'd think that they would be front and center on the global terrorism scene and yet they're not. Paris or Marseille should be the European "hubs" for global terrorism, not London.
That said, the reason why terrorism is kept so well under control in France may have a lot to do with the country's superbly efficient counter-terrorism units. A system that other countries don't dare put in place for fear of being in clear violation of civil liberties, France has not hesitated to implement it. It clearly works. France has very little chance of ever becoming a terrorism haven. They've just gotten too good at nipping it all in the bud.
Some links that may be of interest:
BBC NEWS | Europe | French jihadis thrive on alienation
France and Its Muslims | Foreign Affairs
Islamic terrorism in Europe: After Van Gogh | The Economist
Fighting Terrorism: Lessons from France - TIME