Year US Dollars 1970 3432690000 1971 4682279000 1972 5814545000 1973 7270798000 1974 9100923000 1975 11497813000 1976 14010055000 1977 16470547000 1978 18045709000 1979 18623753000 1980 20937702000 1981 22761141000 1982 25133287000 1983 30229381000 1984 32025242000 1985 36714624000 1986 42914289000 1987 52526345000 1988 54053868000 1989 59380148000 1990 69848499000 1991 79523030000 1992 87978588000 1993 89146947000 1994 107808954000 1995 124388680000 1996 128988712000 1997 136322465000 1998 151466804000 1999 151788588000 2000 144031659000 2001 132693891000 2002 128429103000 2003 134358681000 2004 138028986000 2005 142120094000 2006 135959423000 2007 147817590000 2008 157906449000 2009 179394964000 2010 198268605000 2011 219619633000 2012 252555891000 2013 265452911000 2014 292970691000 2015 308221474000 2016 316430908000