But religion can grow even in otherwise secular societies. For example, in Israel, the ultra-Orthodox Jews comprised just about five percent of the nation's primary schoolchildren in 1960, but by the start of the twenty-first century, one third of Jewish first graders in Israel came from this religious sect. Ultra-Orthodox Jewish women in Israel had on average 7.5 children compared to their more mainstream counterparts with just over two in the early 2000s. In Europe, immigration from the Middle East and Africa is an engine of religious growth. Children of immigrants tend to be about as religious as their parents and consider their religion to be a marker of their ethnic identity, thereby insulating themselves from the secularizing forces of the host society. The other engine is comparatively high fertility and religious endogamy. In France, a white Catholic woman had half a child more than her secular counterparts in the early 2000s; in Spain, that number was 0.77. In the Netherlands, the youngest villages belong to Orthodox Calvinists, who comprised 7% of the Dutch population by the early 2000s. In Austria, the number of people below the age of 15 who were Muslims rose past the 10%-mark in the first decade of the twenty-first century. In the United Kingdom, over 90% of Muslims married other Muslims by the turn of the millennium, and it is well known that children born into an interfaith marriage tend to be less religious than their parents. Interfaith marriage is in fact a vehicle of secularization. Ultra-Orthodox Jews comprised just 12% of the British Jewish population but three quarters of Jewish births at the start of the twenty-first century. (This group is projected to make up the majority of Anglo-American Jews by 2050.) In the United States, Catholicism will become the largest religion by 2040 despite considerable losses to secularization and conversion to Protestantism thanks in no small part to the fact that Latino Catholics had a fertility rate of 2.83 compared to the national average of 2.03 in 2003. Such religious demographic changes will bring about social and political ramifications later in the century.