XBLIG is part of it going by that huge number.What they aren't telling you is that I MA3D A GAM3 W1TH Z0MB1ES 1N IT!!!1 is responsible for $3.8 billion of that.
That game was awesome fun for $1. So were the many other games I bought, including twin stick shooters, zombie estate and ZP2kx. Lots of excellent $1-5 games better than $10-15 XBLA games..... but also lots of junk to sift through.