From 2004 to 2012, imports to Indonesia tripled, as large portion of the population entered middle-class and propelled higher purchases of oil and consumption goods. However, starting in mid-2013, imports have been declining due to low commodity prices and weak domestic consumption and investment. Main imports products are: oil and gas (around 17 percent of total imports), nuclear reactions, boilers, mechanical appliances (19 percent); iron and steel (5.4 percent), organic chemical materials (4.8 percent) and vehicles (4.5 percent). Main import partners are: China (25 percent of the total imports), Japan (11 percent), Singapore (7.6 percent), Thailand (6.8 percent) and the United States (6.4 percent).