 The number of Hungarians in Slovakia increased from 518,782 in 1961 to 567,296 in 1991.The number of self-identified Hungarians in Slovakia decreased between 1991 and 2001, due in part to low birth rates, emigration and introduction of new ethnic categories, such as the Roma.Also, between 1961 and 1991 Hungarians had a significantly lower birth rate than the Slovak majority (which in the meantime had increased from about 3.5 million to 4.5 million), contributing to the drop in the Hungarian percentage of the population.