In the two decades since the country emerged from dictatorship, Chile has consistently maintained friendly relations with the United States. Serving as a reliable--if not always very public--ally, Chile has worked with the United States to advance democracy, human rights, and free trade in the Western Hemisphere. Chile and the United States also maintain strong commercial ties. Trade has more than doubled to over $15 billion since the implementation of a bilateral free trade agreement in 2004, and an income tax treaty designed to boost private sector investment was signed in February 2010 and is awaiting submission to the U.S. Senate for ratification. Additional areas of cooperation between the United States and Chile include renewable energy and regional security issues. President Sebastián Piñera of the center-right "Coalition for Change" took office in Chile in March 2010, bringing an end to 20 years of governance by a center-left coalition of parties known as the Concertación. During its time in power, the Concertación enacted constitutional changes to strengthen civilian democracy, took steps to address human rights violations that had occurred during 17 years of military rule under General Augusto Pinochet, and supplemented free market economic policies--which had been implemented during the dictatorship--with ...