Updated graph on laws on carrying
No Lawyers, Only Guns and Money has an updated one online. It says something that things are changing so quickly (and all in the direction of greater freedom) that you have to make sure any chart is up to date.
In terms of population, they calculate that 65% live in "shall issue" states, 27% in "may issue," 7% in "don't need" and 0.4% in "can't get" states.
It's not so many years ago, I think up 'till the mid 1980s, that the entire country was, in terms of concealed carry, either "can't get" or "may issue," Vermont being the one exception. (Like many western states, Arizona was "can't get" for concealed carry and "don't need" for open carry).