Some users create logs of their hitchhiking mileage.
Here is a discussion about keeping hitchhiking statistics. Further, Prino has a computer program to record the trips and keep easily track and statistics of them. The program can be downloaded from Prino's Google drive . The convoluted format of the input to the program is described in Keeping statistics.
Note from Prino: The programs don't record the trips, you will have to manually enter them in a simple text file. The programs just process this file and produce a number of more (or less) useful output files that you can massage to put on your own site.