Both axis are per capita. The horizontal is log GDP while the vertical is linear energy consumption. I assume the bubble size is population.
I see two things. Obviously the US, and some smaller countries, seem pretty inefficient.
More interesting is how much energy this suggests it is going to take to pull India and China up by a factor of 10 to 30. That ain’t going to happen on current energy flows!
I plucked that chart here.
An alternate view of the Y axis here.