Interesting stuff, it appears to be their own data (I'm guessing aggregated from sources like the UN registry and observation). I was curious about the statistics on satellite missions so I put it into a table:

  Operational satellites by mission:
  total                   2154
  Communications          740
  Scientific              592
  Navigation              135
  Technology Development  109
  Earth Observation       99
  Surveillance            58
  Engineering             20
  Weather                 13
  Not Recorded            8
  Early Warning           3
  Search and Rescue       1
  Space Station Flight    1