Wikipedia has a page listing CO2 emissions by country (Here).
The most recent data they have seems to be from 2015, though I doubt things have changed significantly since then.
China is by far the largest emitter in the world with a total for that year of 10,641,789 Kt. The USA was second at 5,172,336 Kt.
What’s interesting is that you can sort the list of countries by emissions per capita. Looking at the data this way, Australians emit more CO2 than Americans, at 18.6 tonnes per annum versus 16.1. The UK ranks 25th with 6.1 tonnes.
This coming year I’ll be looking at ways of reducing the amount of CO2 I’m responsible for: cutting car use; reducing the gas and electricity used in this house and trying to reduce purchases of stuff destined for landfill. Food miles are something to consider too.