The study for the US Air Force by Leon Perkowski in 2006 found that there were at least 15 million Muslims in the EU, and possibly as many as 23 million. They are not uniformly distributed, of course. According to the US's Migration Policy Institute, residents of Muslim faith will account for more than 20 per cent of the EU population by 2050 but already do so in a number of cities. Whites will be in a minority in Birmingham by 2026, says Christopher Caldwell, an American journalist, and even sooner in Leicester. Another forecast holds that Muslims could outnumber non-Muslims in France and perhaps in all of western Europe by mid-century. Austria was 90 per cent Catholic in the 20th century but Islam could be the majority religion among Austrians aged under 15 by 2050, says Mr Caldwell.