Interesting analysis, once I got it to work. (I have my zsh configured to put history in ~/.zsh_cache/history, not one of the default files. I don't use oh-my-zsh, either.)

If I get to the point where I want to play with this, I'll probably fork it and propose some changes back. It also strongly suggests that I should blow away my history because there's some unusual values reported because of my work.