Returns the proportion of the U.S. population in six racial groups in a given year. Group definitions necessarily follow those used by the Census Bureau in its surname tables:
white
: Non-Hispanic White aloneblack
: Non-Hispanic Black alonehisp
: Hispanic, any raceasian
: Non-Hispanic Asian, Native Hawaiian, or Pacific Islander aloneaian
: Non-Hispanic American Indian/Alaska Nativeother
: Non-Hispanic, two or more races, or other race