Well, this turned out to be quite the odyssey.
Interesting question, sez I. Poke around some.
So, first I got the 2007 state populations of 18+ from
WISQARS. That comes out in .csv form, so I had my Excel data to start.
Then, realizing that we have some folks in prison or jail, or on probation or parole, I looked at the
Sourcebook of Criminal Justice Statistics. It's unfair to some states, of course, but the average % of the population in those 4 categories is about 6, so I subtracted 6% of that 18+ population across the board.
Then I started looking for CCW permit stats. What a pain!
There seems to be a decent selection at
http://www.legallyarmed.com/ccw_statistics.htm - the author points to sources, and quick checks of a few were right, so I just adopted those, rounding to the nearest 1,000.
I was able to research and find additional numbers: for CA - 40,000, Maine - 12,000, Nevada - 24,000, Oklahoma - 90,000.
But Delaware? New Jersey? New York? West Virginia? Montana? Bah!
So, with the numbers I could find, I get an average of 3.1% of the eligible population has a permit, with Pennsylvania on top with 6.9%.
Just a reasonable guess, I think.