Year 0 to 10 years Over 10 years
1970 30.6 69.4
1980 39.6 60.4
1990 43.8 56.2
2000 42.4 57.6
2010 34.7 65.3
2013 28.4 71.6
2014 28.1 71.9

Source: Pew Research Center tabulations of 1970-2000 decennial censuses and 2010, 2013 and 2014 American Community Surveys (IPUMS)