During the eight years of the Reagan presidency, the number of legal abortions increased by more than 5 percent; during the eight years of the Clinton presidency, the number dropped by 36 percent. The overall abortion rate (calculated as the number of abortions per 1,000 women between the ages of 15 and 44) was more or less stable during the Reagan years, but during the Clinton presidency it dropped by 11 percent.

There are many reasons for this shift. Yet surely the traditional Democratic concern with the social safety net makes it easier for pregnant women to make responsible decisions and for young life to flourish; among the most economically disadvantaged, abortion rates have always been and remain the highest. The world's lowest abortion rates are in Belgium and the Netherlands, where abortion is legal but where the welfare state is strong. Latin America, where almost all abortions are illegal, has one of the highest rates in the world.

And here is a column by a Christian ethics professor containing partial numbers from 2001 onward, consistent with the research detailed above.