How many songs can you sing?

[Hazard]

I karaoke to Ayu. A lot. So there are quite a few of her songs that I have memorized. I was wondering if anyone else karaoke's to her and, if so, what songs can you sing without looking at the lyrics? These are the ones I know:

A Song for XX
POWDER SNOW
For My Dear...
parts of Trauma
parts of immature
Boys & Girls
parts of End roll
parts of P.SII
appears
parts of monochrome
parts of Duty
parts of vogue
parts of End of the World
SURREAL
parts of Key~eternal tie version~
I am...
Connected
evolution
NEVER EVER
M
Dearest
parts of no more words
Endless Sorrow
parts of WE WISH
Real Me
Free & Easy
parts of Heartplace
parts of Over
HANABI
parts of everywhere nowhere
parts of Dolls
parts of Voyage
ANGEL'S SONG
parts of Greatful days
ourselves
HANABI~episode II~
No way to say
parts of forgiveness
Memorial address
Moments
INSPIRE
GAME
parts of CAROLS
RAINBOW

Wow, that's a lot more than I thought it would be...
I can also sing along with practically all of her songs if I've got the lyrics(romanized, of course) in front of me. Is this unhealthy?