2002

Here's a little variation on the list from Publisher's Weekly divided between trades and mass market, thus the duplicates in each category, since they are looking at total sales.

TRADE PAPERBACKS
1. Fix-It and Forget-It Cookbook, Dawn J. Ranck and Phyllis Pellman Good 19 copies on LT
2. The Two Towers, J.R.R. Tolkien. 9,783 copy
3. The Lord of the Rings, J.R.R. Tolkien 13,089
4. The Return of the King, J.R.R. Tolkien 9,434
5. The Fellowship of the Ring, J.R.R. Tolkien 10,384 copies
6. What to Expect When You're Expecting, 3rd ed. Heidi Murkoff, Arlene Eisenberg and Sandee Hathaway 706 copies
7. Sula, Toni Morrison 1,739 copies
8. A Child Called It, David Pelzer 1,315 copies
9. Empire Falls, Richard Russo 2,465 copies
10 . Fast Food Nation, Eric Schlosser 785 copies

MASS MARKET

1. The Summons, John Grisham 1,741 copies
2. The Lord of the Rings: The Two Towers, J.R.R. Tolkien 9,783 copies
3. Face the Fire, Nora Roberts 687 copies
4. The Villa. Nora Roberts 437 copies
5. Midnight Bayou, Nora Roberts 421 copies
6. On the Street Where You Live, Mary Higgins Clark 472 copies
7. The Lord of the Rings: The Fellowship of the Ring J.R.R. Tolkien 12,089 copies
8. The Hobbit, J.R.R. Tolkien 17,934 copies
9. 1st to Die, James Patterson 1,327 copies
10. The Kiss. Danielle Steel. 1,109

Looks like Tolkien hit the jackpot.

I've read all the Tolkiens, What to Expect, and the three Nora Roberts titles. With the possible exception of Nora Roberts, I owned them all well before 2002, though.

Here's something else a little different.

ALMANACS, ATLASES & ANNUALS

1. The World Almanac and Book of Facts 2003. Edited by Ken Park. Annual. World Almanac
2. Guinness World Records 2002 edited by Antonia Cunningham. Revised.
3. The World Almanac and Book of Facts 2002. Edited by Ken Park.
4. J.K. Lasser's Your Income Tax 2003. J.K. Lasser.
5. The Ernst & Young Tax Guide 2003. Ernst & Young.
6. AAA North American Road Atlas. AAA
7. The World Almanac for Kids 2003. Edited by Kevin Seabrooke.
8. What Color Is Your Parachute 2003. Richard Nelson Bolles.

varielle,
I'm glad you didn't attempt to figure out how many copies of the almanacs etc were in LT libraries. Serials don't combine very well, as you have to look everywhere in the lists to find them for combining. These are edited, not authored volumes for the most part.
But it is good to see these in a list.

As for the trade paperback list, the Harry Potter books are conspicuous by their absence, as they are deemed as children's books only.

I have read all four tolkiens, fast food nation and a child called it - oh and the what color is my parachute book.

The World Almanac has now been put into a series listing, and there are 133 editions (incuding variations within the same year). The series with mostly latter year covers is here: http://www.librarything.com/series/The+World+Almanac+and+Book+of+Facts

I've read the Tolkien and Fast Food Nation, though I made the mistake of reading the latter on an upset stomach.