Eh, that doesn't necessarily provide fair statistics. Lets use this contrived example with made up numbers where the US has a population of 500 million and China 1 billion.
US per capita: 1000 tons of CO2 per year
China per capita: 1000 tons of CO2 per year.
Looks like China is twice as good. But if you break out population statistics and 500 million of them live in mud huts and produce almost no CO2, then the other half that have moved to US like living conditions produce US like carbon.