As in how many posts are made per day with each of the more popupar tags? I find difficult to answer this question myself, since post dates aren't shown in any obvious place.
The global feed sorted by time gives a pretty good idea of post activity. But we just had an influx of new people.
You could compare the entire site's activity to a middle-sized subreddit. However, commenting and post activity seems to vary in waves.
None of the individual tags is active enough to be considered a stand-alone community.