Even though Mexico is a very ethnically diverse country, research about ethnicity has largely been a forgotten field, in consequence of the post-revolutionary efforts of Mexico's government to unify all non-indigenous Mexicans under a single ethnic identity (that of the "Mestizo"). As a result, since 1930 the only explicit ethnic classification that has been included in Mexican censuses has been that of "Indigenous peoples". Even then, across the years the government has used different criteria to count Indigenous peoples, with each of them returning considerably different numbers ranging from 6.1% to 23% of the country's population. It is not until very recently that the Mexican government begun conducting surveys that considered other ethnic groups that live in the country such as Afro-Mexicans who amount to 2% of Mexico's population or White Mexicans who amount to 47% of Mexico's population (with the criteria being based on appearance rather than on self-declared ancestry). Less numerous groups in Mexico such as Asians and Middle Easterners are also accounted for, with numbers of around 1% each.