My data comes from the site itself - Google Analytics and other tracking tools embedded in the site which look primarily at IP addresses and such.
The site mentioned by redwing does not have access to this data - they use various other algorithms to "guess" about the data, and as you can see, their guesses are rather inaccurate.
Is the last yr of visitor data posted anywhere (I did a quick search but didnt find it - perhaps I had a man look?) if not it would be interesting to compare to that early 2013 data.