Higher win percentages are possible:

http://www.facebook.com/photo.php?fbid=3897685124017&set=a.2776133565929.2145585.1335803656&type=1&theater

My current longest winning streak is 25.

The trick is to not give up until you've proven to yourself that a game is unwinnable.

I think on average, about 80% of these games are winnable, if you don't give up.