You’re doing a good job presenting some of the data. There are problems with the data though. Now that the data is out in public, people are going to plow through it and as it is filtered by common scientific sense (and not just by people looking for global warming), the average will become valuable.
Well, that's petty much what the Berkeley Earth Project did: started from scratch on the the data, took a fresh look at the statistical methods (and even managed to extend their data set back a bit further than had been done previously - which was a useful contribution)... and came up with almost exactly the same result as previous methods.
So you have to ask "How many bits of the apple is it reasonable to take", and expect to get a different result?