About 28% of the Canadian population are of British descent, while 23% are of French origin. Another 15% are of other European background, about 26% are of mixed background, 6% are of Asian, African, or Arab descent, and some 2% are of aboriginal or Métis (mixed aboriginal and European) background. In the late 1990s, Canada had the highest immigration rate of any country in the world, with more than half the total coming from Asia, and immigration has continued to contribute significantly to the nation's population growth. Over 75% of the total population live in cities. Canada has complete religious liberty, though its growing multiculturalism has at times caused tensions among ethnic and religious groups. About 43% of the people are Roman Catholics, while some 23% are Protestant (the largest groups being the United Church of Canada and Anglicans). English and French are the official languages, and federal documents are published in both languages. In 2001, about 59% of Canadians cited English as their mother tongue, while 23% cited French.