Immigration in the 20th century differed significantly from that of the previous century. The 1920s saw great influxes from Italy and Poland; in the 1930-50s immigrants came from Spain and Portugal. Since the 1960s however, the greatest waves of immigrants have been from former French colonies: Algeria (1 million), Morocco (570,000), Tunisia (200,000), Senegal (45,000), Mali (40,000), Cambodia (45,000), Laos (30,000), Vietnam (35,000). Much of this recent immigration was initially economical, but many of these immigrants have remained in France, gained citizenship and integrated into French society. Estimates vary, but of the 60 million people living in France today, close to 4 million claim foreign origin. This massive influx has created tensions in contemporary France, especially over issues of "integration into French society" and the notion of a "French identity", and in recent years the most controversial issues have been with regards to Muslim populations (at 7%, Islam is the second largest religion in today's France; see Islam in France).