The Kyoto Protocol is a 1997 international treaty that came into force in 2005. In the treaty, most developed nations agreed to legally binding targets for their emissions of the six major greenhouse gases. Emission quotas (known as "Assigned amounts") were agreed by each participating 'Annex I' country, with the intention of reducing the overall emissions by 5.2% from their 1990 levels by the end of 2012. Between 1990 and 2012 the original Kyoto Protocol parties reduced their CO2 emissions by 12.5%, which is well beyond the 2012 target of 4.7%. The United States is the only industrialized nation under Annex I that has not ratified the treaty, and is therefore not bound by it. The IPCC has projected that the financial effect of compliance through trading within the Kyoto commitment period will be limited at between 0.1 and 1.1% of GDP among trading countries.