1) You're friends with me, related to me, married to me, or otherwise contractually obligated to act interested in my blog before I've even loaded any content onto it.
2) You're bored enough to have read through every post in at least one category to get back to the beginning. You might be feeling a sense of accomplishment mixed with shame, kind of like when you eat an entire pizza by yourself. (I speak from experience as someone who's read the complete oeuvre of Hyberbole and a Half and considers any pizza under 16" a single-serving pie.)
Which category you fall into is basically a function of how long ago I wrote this post:
This graph doesn't help you in any way. I mostly just drew it in lieu of folding the two loads of laundry on the living room floor.