I must say that is quite impressive that you are winning almost 1/4 of your games
I just found this link for a minesweeper solver that claims 14% for expert: http://www.nuprograms.com/minedefuser.html
Here's quite a scholarly link as well, they ended up with an avg. 25% for expert with a high of 30%, so Dante's is probably all it can be :-)
http://www.dcs.warwick.ac.uk/~kasper...les/report.pdf