"Last year" means 2007... till next January.
EDITED: no, now it means 2013!!
"The very best" means you can name only one.
It also should be a new read, not a re-read, even if your tenth time through The Waste Lands was your last year's best reading experience.
Mine was definitely The Bear Went Over the Mountain by William Kotzwinkle! I can't thank Lisa enough.