 With a similar methodology, the American Sociological Association obtained a percentage of 18.8% having its higher frequency on the North region (22.3%–23.9%) followed by the Center region (18.4%–21.3%) and the South region (11.9%).Another study made by the University College London in collaboration with Mexico's National Institute of Anthropology and History found that the frequencies of blond hair and light eyes in Mexicans are of 18% and 28% respectively, surveys that use as reference skin color such as those made by Mexico's National Council to Prevent Discrimination and Mexico's National Institute of Statistics and Geography reported a percentages of 47% in 2010 and 49% in 2017 respectively.A study performed in hospitals of Mexico City reported that an average 51.8% of Mexican newborns presented the congenital skin birthmark known as the Mongolian spot.