You can sometime see "Decreasing year-over-year development activity" in the project overall report. What does it mean? How is activity computed? For example is it the number of commits? If it is, the case, I would suggest to use the number of files committed instead. For example some people commit one file at a time, and others do a lot at once, but activity wise we cannot say one has more activity than the other if they changed the exact same number of files.