Interesting -- I read more SLOWLY if I am re-reading a good book. I already know how it ends, so this time I need to catch all the tiny details and fore-telling bits that I chewed too quickly the first time!
I just re-read the Lois McMaster Bujold Vorkosiverse, LOTR, Sayers Wimseys, Gabaldon, all just last year. Oh, and the Robin Hobb's Assassin's Apprentice trilogy, and then the next two Fritz and ____ trilogies for the first time (the last is only 2 books so far; I'm hoping it'll be finished, maybe this year??)
edit: I guess the Robin Hobbs re-reads were this year, not last. So, 1.25 years worth above. Plus LOTR spanned the previous Christmas. So maybe 1.3 years.