Percent of gun owners in different countries?

I tried to research this question and if anyone has any good numbers I haven’t found them. Most sites take the total number of guns known to be present in a country and divide by the population, which at least in the case of the US wildly skews the numbers, given that so many gun owners own multiple guns. In places where registration is incomplete or non-existent a count of gun owners simply might not be possible. What are the best guesses available?

Here’s some “percentage of household with guns” figures. It’s nearly 20 year old data, though, as well as being badly formatted:

The figures given for Switzerland sound low. Maybe they aren’t counting the active militia.