The book, written by Joan Sauers, also discusses sexual fantasies, threesomes, how sex changes as women get older and orgasms.
Women surveyed only gave age, state of residence and occupation, but the findings imply that a young, Internet-savvy population mostly took part in the poll.
Author Sauer was impressed by the respondents' honesty.
"I think women do talk to each other more than men do about their sex lives, but there are the really personal things we don't even tell our best friends, and I think this is where the anonymity of this survey provides important material," Sauer said. "It became a place where women could vent about what was right and wrong about their sex life, and I got 7,000 pages of material."
Sauers wrote "Sex Lives of Australian Teenagers" using a similar online survey two years ago, and she said she found two surprises in the results.
"The first was that younger women in their 20s felt the most guilt about cheating on their partner while older women tended to be more forgiving of themselves," she said. "I think it shows the older we get, the more complicated our sense of moral relativism becomes.
"And second, I was stunned to find the number of women who still don't know it's illegal to be forced to have sex by their husband. They still have this sense of debt that part of the marriage vows include having sex even if they desperately don't want to."
In the section on sexual fantasies, the survey showed that a liaison with another woman was the prevailing imaginary encounter for 57 percent of the women surveyed.