Ah-ha!

I feel exonerated! These books all had less than 50% chance of being a bestseller:
A Tree Grows in Brooklyn--10.2%
The Cae for Christ--35.9%
White Oleander--41.4%
The Bridges of Madison county--35.9%
Tuesdays With Morrie--45.6%
Harry Potter and the Sorcerer's Stone--45.6%
The Da Vinci Code--39.5%
Pet cemetery--35.9%

So I think I'm probably okay, don't you think?