(CNN)Here's a look at what you need to know about abortion statistics in the U.S.
January 22, 1973 - Roe v. Wade - The U.S. Supreme Court, in a 7-2 decision, affirms the legality of a woman's right to have an abortion under the Fourteenth Amendment to the Constitution.
The most common method of legal abortion (before 13 weeks) is surgical vacuum aspiration.
"Partial birth abortion" is a controversial name for intact dilation and evacuation (or extraction). A ban on the procedure was upheld by the Supreme Court in 2007.
The following is the number of abortions reported to the CDC:
The number of abortions in the U.S. increased gradually from 1973, then peaked in 1990 and has been on the decline since then.
The abortion ratio increased from 196 per 1,000 live births in 1973 to 358 per 1,000 in 1979 and remained nearly stable through 1981.
The ratio peaked at 364 per 1,000 in 1984 and has steadily declined since then.
2011 is the most recent year for which the CDC has released statistics. The reporting areas are the District of Columbia; New York City; and 47 states, excluding California, Maryland, and New Hampshire.
From 49 reporting areas, 730,322 legally induced abortions were reported to the CDC. This is a decrease of 5% compared to 2010. There were 219 abortions for every 1000 live births for women aged 15-44.
91.4% of 2011 abortions were performed at or less than the 13th week of gestation. Of those 64.5% were performed at or less than the eighth week. 19.1% of all 2011 abortions were medical abortions.