A shocking look inside intimate relationships and what goes on behind closed doors. One in 4 women surveyed by the government say they were violently attacked by their husbands or boyfriends.

The survey, released by the CDC Wednesday, marks the beginning of a new annual project to look at how many women say they've been abused.

One expert called the new report's estimate on rape and attempted rape "extremely high" -- with 1 in 5 women saying they were victims. About half of those cases involved intimate partners. No documentation was sought to verify the women's claims, which were made anonymously. The CDC says the numbers from the survey could actually be higher, as many victims never tell.

As many as 29 million women say they have suffered severe and frightening physical violence from a boyfriend, spouse or other intimate partner. That includes being choked, beaten, stabbed, shot, punched, slammed against something or hurt by hair-pulling. That number grows to 36 million if slapping, pushing and shoving are counted.

The CDC report is based on a randomized telephone survey of about 9,000 women.