I tend to think differently as well and don't assign a 'tolerance' percentage.
What I try to do, as well as a few reciprocals which I have cut back on, is to link out to trustworthy sites that I feel will provide useful information for my visitors.
I believe that having a good quantity of outward links to quality sites helps my
SEO efforts as much as reciprocal links, even from the same site. The web is just a collection of links and if I link to quality sites, who I presume do the same, it should provide the search engines a natural linkage of quality sites that they will trust.
Of course, this is really just a utopian dream of mine but I'm sticking with it!!
I've voted 30% but really have never measured the number of non-reciprocated outward links from my site so it's a bit of a guess. Maybe I should have voted, "I don't care" but thought an estimated percentage would be more beneficial for the poll.