After Donetsk coffee'n'code announcement in a popular Russian collective blog Habrahabr, almost a dozen of new people subscribed to the mailing list. The plot above shows the number of new subscribers in last 20 months.
The code is available on Github. A blog post by Ian Lewis about Python date range iterator was helpful to write an iterator over months. The plot style (custom tick labels) is heavily based on Mark Larsen's answer to a Stackoverflow question.