SOBO '16 Survey
This data is gathered from 75 SOBO hikers who attempted the PCT in 2016. All of the dates are based on trail registers or conversations with specific SOBOs about their start and end dates. The total number of SOBO hikers who quit is more speculative. It's primarily based on a list Happy Feet kept of people he met/heard about on trail, US/Mex border trail registers, and a the SOBO '16 Survey.
2016 SOBO Thru hiker survey