This shows numerous crime total since 1960, which seems like a fair metric as few women at all are raped above the age of 45(~2%), and there aren't many people at all above the aged of 95.

The total for rapes is 3,904,342; this is rapes of men and women.

Now, obviously not all rapes are reported, but let's address the various 1 in 4/5/6 statistics, and potential flaws from going by surveys alone.

As of 2012, ~162,760,000 women in the US.

1 in 4 would mean 40,690,000

1 in 5 would mean 32,552,000

1 in 6 would mean 27,126,666

Reporting rates vary over the years, with numbers from the NCVS's from the 90s being 30-40% and in 2010 being 50%. It's a little harder to track down the numbers before 1995(working on it, once I do I'll have a better picture overall).

So if the 1 in 6 stat is true, that would mean that only 1 out of every 7 rapes was reported, meaning 86% have gone unreported.

If the 1 in 5 stat is true, that would mean 87.5% have gone unreported.

If the 1 in 4 stat is true, that would that 90% of rapes have gone unreported.

Keep in mind that the documented number isn't just the rape of women, so the actual number is lower. I know we have the whole "definition of rape" issue, but that number is based on the definition of rape, and let's say 90% of that number is female victims, taking it to 3,513,907.

So either the surveys from the Bureau of Justice are wrong, or the surveys yielding lifetime rates are wrong. It's also possible that since they're surveys, they're both very flawed.