Of the 69,117 active threads last year, 8,865 were started and ended by the same user (this does not include the 2,954 threads with no replies mentioned in my OP). This works out to be a 13% thread-suicide rate.
These 8,865 threads were started (and ended) by 2,853 different usernames, meaning that out of 7,513 thread starters, 38% killed their own threads.
So who killed the greatest number of their own threads?
1. Johnny L.A. (87 threads)
2. Eve (54)
3. Quasimodem (49)
4. Lobsang (44)
5. ccwaterback (41)
6. Tuckerfan (40)
7. Joel (39)
8. NoClueBoy (35)
9. ivylass (34)
10. Revtim (34)
The 2,954 threads that received no replies were started by 1,656 different usernames, and the honors go to:
1. Bosda Di'Chi of Tricor (26 threads with no replies)
2. ralph124c (23)
3. gypsymoth3 (23)
4. Sampiro (15)
5. Earl Snake-Hips Tucker (15)
6. astro (14)
7. Lobsang (14)
8. Tuckerfan (14)
9. Wesley Clark (14)
10. Jinx (12)