Forty years ago, the US Supreme Court decided in Roe v. Wade that states could not ban first-trimester abortions. Wonkblog's Sarah Kliff takes a look at what's been happening since; her charts document the decline in the number of US abortion providers from the mid-1970s to early 2000s (holding steady since then); an increase in state abortion restrictions, with 92 enacted in 2011 alone; and an increase in the proportion of abortion patients who are low-income and minority. Perhaps most surprising to those of us already aware of these trends is the result of a recent survey: only 44% of…