Happy New Year everyone!
I know that its been a long time since the poll was over, and I haven't told you the answer yet. Sorry. Well here's the answer:
China is the leading country that emits CO2--by far. The USA is the second, followed by the European Union, Russia, and India.
Here are a few links for you to get the full scoop:
http://en.wikipedia.org/wiki/List_of_countries_by_carbon_dioxide_emissions

http://www.mnn.com/earth-matters/climate-weather/stories/the-road-to-copenhagen-which-countries-emit-the-most-co2