Maybe I'm waaay wrong on this, but aren't married women the biggest consumers of birth control?

[Contrary1]

44. You are correct. As of August 2013:

WHO USES CONTRACEPTIVES?

• More than 99% of women aged 15–44 who have ever had sexual intercourse have used at least one contraceptive method.[5]

• Some 62% of all women of reproductive age are currently using a contraceptive method.[2]

• Eleven percent of women at risk of unintended pregnancy are not currently using any contraceptive method.[2]

• The proportion of women at risk who are not using a method is highest among 15–19-year-olds (18%) and lowest among women aged 40–44 (9%).[2]

• Eighty-three percent of black women who are at risk of unintended pregnancy currently use a contraceptive method, compared with 91% of their Hispanic and white peers, and 90% of Asian women.[2]

•Ninety-two percent of at-risk women with incomes of 300% or more of the federal poverty level are currently using contraceptives, compared with 89% among those living at 0–149% of the poverty line.[2]

•A much higher proportion of married than of never-married women use a contraceptive method (77% vs. 42%). This is largely because married women are more likely to be sexually active. But even among those at risk of unintended pregnancy, contraceptive use is higher among currently married women than among never-married women (93% vs. 83%).

http://www.guttmacher.org/pubs/fb_contr_use.html