I broke it down into currently owned and historically owned (since I've sold many) - I'm sure I'm missing a few titles here but anyway...
Currently own
Nintendo 21 (31%)
EA 6 (9%)
Konami/Namco/Temco 6 (9%)
Ubisoft 5 (7%)
Capcom 5 (7%)
LucasArts 3 (4%)
XSeed/NIS 3 (4%)
Rockstar/T2 2 (3%)
Eidos (SE) 2 (3%)
Others 6 (9%)
Going to all titles I've ever purchased - the title count nearly doubles but interestingly the percentages stay the same except Nintendo loses 2% (to 29%) and Others gain 3%.