I don't think this is really very important at all these days. Google (which is the only company anyone counts in this sort of thing) have realized people manipulate their links and essentially made this ratio defunct. It's much more important to have valid, often updated, original content than pretty much anything else. Okay, high PR links to you help too!
As for PR (Page Rank), it's a bit stupid in a way. The only people who really care about it are advertisers, and if you advertise too much on your site, Google lowers your PR. Catch 22. No one else really gives a frack either.