Wow, Harold, so sorry I didn't see this before!
I think it's really difficult to find an exact percentage with the resources on the net (but maybe that's just inspiration for me to get out of my chair and check out the periodical and accademic journal archive in my university's library). I found
this site which suggests that 80% of women who had abortions after being sexually victimized said that they regretted it. But since the title of that website is "Physicians for Life," so the source is probably biased.
That's the other problem-- depending on the source, the results are highly likely to be biased, and the research probably wasn't exactly impartial.
For example, the NARAL Pro-Choice group in California claims that the majority of women who have abortions feel "
relief, not regret."
It all depends on your source, really, so in short... I don't know. I'd imagine that at least SOME women would regret their choice, if not the majority, but since every survey I've found so far has been skewed, I can't say what that number is for sure.
Maybe my library will have more reliable information. I'll get back to you.