The American Library Association has a list of the 100 most frequently challenged books of 1990-2000 here. They also have a list of the 100 most challenged books of 1990-1999 here.
I came across this because I started reading “The Catcher In the Rye” and I was just browsing around online about it. I didn’t realize that it was so controversial.
I think that it is cool that the ALA is keeping track of these things.