The International Energy Agency tracks CO₂ emissions from fossil fuel combustion, the leading contributor of greenhouse gas emissions. Data comparing 2011 emissions to the baseline year of 1990 are shown here. While some nations did have a significant drop in CO₂ emissions, others actually increased their emissions. Overall, the Annex 1 nations of the Kyoto Protocol (developed nations that committed to emission targets) reduced emissions and exceeded their Kyoto target of a 4.7% reduction by 7.4%. Much of this reduction was due to the economic restructuring of many of the countries of the former Soviet Union and Eastern bloc. The United States, which did not ratify the protocol and was not bound by its target of a 7% reduction, actually increased CO₂ emissions by 8.6%. Developing nations were not given any reduction targets and many had an increase in emissions. Overall, compared to 1990 emission levels, the world saw a net increase of 49.3%.