You made an assumption about what I looked at.
In case you came up with a solid source I checked the below reference link. From there I went to four other links, two of which claiming to be data, and have the same result. The information has already been massaged and there is a reference point of 0.0 that has no meaning.
Therefore we remain in the same place accepting as data the material that someone else has decided is sufficient to prove their point.

Quote Originally Posted by leo9 View Post
If you can't be be bothered to follow the links, here's another that connects to the original data sources:
http://www.metoffice.gov.uk/climatec...xplained5.html