The idea is to share memory for commonly used values. There is no real significance to the actual array sizes; they were chosen to share a reasonable number of instances without consuming too much memory (for example, see the commit message of https://github.com/jacoco/jacoco/commit/3e5b0801b79e94cba9317f18e507d5e65737ce2c). I suspect the values could be changed if you had interesting data points.