Year US Dollars 1970 2329426000 1971 3115341000 1972 3932626000 1973 4798033000 1974 5640712000 1975 6626720000 1976 8317652000 1977 10136188000 1978 12541324000 1979 15981335000 1980 18494668000 1981 20652769000 1982 19905764000 1983 20481895000 1984 19647970000 1985 22254001000 1986 21502882000 1987 22471937000 1988 21177809000 1989 19072883000 1990 17792821000 1991 16472059000 1992 16483024000 1993 12708822000 1994 11100631000 1995 10785299000 1996 9409824000 1997 10616367000 1998 10897971000 1999 10978473000 2000 11573165000 2001 12478684000 2002 11400901000 2003 14259748000 2004 14562777000 2005 16159381000 2006 19885771000 2007 26211640000 2008 30493343000 2009 33813839000 2010 32934661000 2011 31724198000 2012 34444376000 2013 36397427000 2014 33078634000 2015 31364245000 2016 29599394000