When one of our thousands of languages has a.) only a -3 code and b.) frequency set to 0, it doesn't necessarily make sense to be calculating statistics for it, especially given we don't even display things with 0. Once we've collected at least one data point nothing should ever stop getting collected (else any graphing gets annoying gaps), but the frequency should also never drop back to 0 after something gets enabled (our one exception, Moldavian, was because of a code change, and has a -2 code anyway).