As of March 2012, 50.4% of U.S. mobile subscribers owned smartphones, up from 47.8% in December 2011, according to a Nielsen survey released Monday. Google’s (GOOG) Android was the most popular smartphone operating system (48.5%), while Apple (AAPL) was the No. 1 manufacturer (32%).

No surprises there.

It’s when the data are broken down by sex and ethnicity that things get interesting. According to Nielsen:

• 67.3% of Asian Americans use a smartphone as their primary mobile handset, more than any other ethnic group.
• Almost three out of five Hispanic mobile subscribers use smartphones
• 54.4% African-Americans own smartphones
• More than half (50.9%) of female mobile subscribers carry smartphones, compared with 50.1% for men.
• More than two out of three 25-34 year olds use smartphones.

Which leaves, I guess, older white men carrying around the bulk of the remaining dumb phones.

For more on the survey, click here.