In spite of that, emigration of Mexicans continued throughout the rest of the 20th century at varying rates. It grew significantly during the 1990s and continued to do so in the first years of the 2000s. In fact, it has been estimated that 37% of all Mexican immigrants to the United States in the 20th century arrived during the 1990s. In 2000 approximately 20 million American residents identified themselves as either Mexican, Mexican-Americans or of Mexican origin, making "Mexican" the sixth-most cited ancestry of all US residents.