The numbers you cite are PPP (Purchasing Power Parity) which is not really relevant to this discussion about the size of a market as it weights GDP by cost of items/living etc.

Mine were straight from Google (e.g.https://www.google.co.uk/search?q=uk+gdp+per+capita+&oq=uK+G...) )

For the relevant Wikipedia link, see:

http://en.wikipedia.org/wiki/List_of_countries_by_GDP_(nomin...