Well, check it out, Wikipedia
beat us to the answer once again. Honestly, they're going to put us out of business one of these days. Well, that is, if either one of us weren't just a volunteer organization.
In any case, I'll summarize the Wikipedia article so it looks like I did some work myself. Space disasters come in several different types, each with their own death rates; in-flight accidents have killed 18 astronauts, training accidents have killed 11 astronauts, and launchpad accidents have killed about 70 ground crew.
About 5% of all people who have been in space have been killed in accidents of some kind. It's more difficult to get percentages of ground crew killed, since their jobs are less in the limelight, and less strictly defined; NASA probably doesn't even keep a total number of "ground crew," and I doubt Soviet Russia did either. It seems to me, though, that being a ground crew worker is the more dangerous job, since accidents that happen on the ground are a) more frequent and b) kill a larger number of people. (The largest accidents involving ground crew killed 126, 48, and 21 people respectively.)
However, the one aspect in which astronaut accidents are more dangerous is fatality--if you're on the ground crew and something goes wrong, you have a chance at coming out alive, with maybe some bad burns or something. (Hey, it's happened.) If, though, you're an astronaut in space and something explodes...well, sorry.
This would make me rethink all my childhood dreams of being on the NASA ground crew...if, that is, I had had any such dreams.