hn, you frame the issue incorrectly, and I almost think it is intentional. It is not what percentage of guns in the country are misused. Rather, it is a comparison between the number used in legitimate self defense versus the number abused so as to kill or harm innocent victims or even the owners themselves.
The numbers are so skewed in the direction of abuse that we at this point can conclude, rather easily, that the claim of the NRA and the gun businesses that we need guns to remain so easily accessible "for safety's sake" is a bald-faced lie.
Overall, handguns make us all much, much more unsafe.
And its not even close.
There have been a slew of studies to try to estimate how many DGU's (Defensive Gun Uses) there are a year. As far as I know the lowest number ever set forth by anyone (we're talking the East German Olympic judge here) with any cred at all is '93's National Crime Victimization Survey. This extreme (low side) outlier still estimated 108,000 DGU's annually. Other studies quickly jump to 800K and up.
The other thing I always find interesting about your stance (and others like you) is to point out the more violence there might be committed by the "bad guys" the harder they want to push legislation that overwhelmingly (and by definition) would act to disarm the "good guys".