I don't know if there are any official stats or not. If so give'em to me. If not then in your opinion or best guess how many corner kicks out of ten will result in goals?
From what I'd seen, I expected it to be about 1 in 30, though the rate is definitely lower than that in MLS. (DC United apparently went a season and a half without a goal off a corner kick, which came out to more than 400 consecutive corner kicks without a goal.)
There was a discussion about it in the magazine "When Saturday Comes". In the Premiership, it was reported that around 1 in 60 goals were scored from a corner kick that was hit straight into the box. The stat was lower for short corners, around 1 in 30, though that could be due to the fact that the vast majority of corners are taken long.
I guess it would change depending on how you define "off a corner kick". 100% (or close) result in a good chance with the ball infront of the net in close. It may take 2-3 shots to get the goal, does that count? They are good scoring chances, but I would say about 1-50 is probably about right.
When the defense isn't set up to stop it, a short corner can be devastating. Check out Esky's 9/18 blast: http://www.mlsnet.com/MLS/mls/awards/2004/sierra/ Last year, the Quakes scored a memorable short-corner goal with a shot from a similar location.
In 2002, I remember seeing the Galaxy get several goals off short corners, and create a lot of scoring chances as well.