remove data entries for non-existing or not-anymore-existing countries

The client dataset client.csv, userstats-combined.csv, and servers.csv contain some two-letter country codes for non-existing or not-anymore-existing countries, i.e. a1, a2, ap, cs, dd, du, eu, which won't be used for serving graphs on the Metrics web-site, but which are included in the data file.

Shouldn't these be removed from the data?