Demographers state that, due to new waves of immigration, the American people through the early 20th century were mostly multi-ethnic descendants of various immigrant nationalities, who maintained cultural distinctiveness until, over time, assimilation, migration and integration took place. The civil rights movement through the 20th century gained passage of important legislation to enforce constitutional rights of minorities. According to James P. Allen and Eugene Turner from California State University, Northridge, by some calculations in the 2000 Census, the multiracial population that is part White (which is the largest percentage of the multiracial population), is as follows: White/American Indian and Alaskan Native, at 7,015,017, White/Black at 737,492, White/Asian at 727,197, and White/Native Hawaiian and Other Pacific Islander at 125,628. Genetic admixture A 2002 study found an average of 18.6% European genetic contribution and 2.7% Native American genetic contribution (with standard errors 1.5% and 1.4% respectively) in a sample of 232 African Americans. Meanwhile, in a sample of 187 European Americans from State College, Pennsylvania, there was an average of 0.7% West African genetic contribution and 3.2% Native American genetic contribution (with standard errors 0.9% and 1.6% respectively). Most of the non-European admixture was concentrated in 30% of the sample, with West African admixture ranging from 2 to 20%, with an average of 2.3%. In 1958, Robert Stuckert produced a statistical analysis using historical census data and immigration statistics. He concluded that the growth in the White population could not be attributed solely to births in the White population and immigration from Europe, but was also due to people identifying as White who were partly Black. He concluded that 21 percent of White Americans had some recent African-American ancestors. He also concluded that the majority of Americans of known African descent were partly European and not entirely sub-Saharan African. More recently, many different DNA studies have shown that many African Americans have European admixture, reflecting the long history in this country of the various populations. Proportions of European admixture in African-American DNA have been found in studies to be 17% and between 10.6% and 22.5%. Another recent study found the average to be 21.2%, with a standard error of 1.2%. The Race, Ethnicity, and Genetics Working Group of the National Human Genome Research Institute notes that "although genetic analyses of large numbers of loci can produce estimates of the percentage of a person's ancestors coming from various continental populations, these estimates may