Year US Dollars 1970 0 1971 0 1972 30147000 1973 108914000 1974 138780000 1975 210868000 1976 524566000 1977 755809000 1978 959936000 1979 3583369000 1980 9762280000 1981 10446728000 1982 10003165000 1983 9128470000 1984 7757570000 1985 7008018000 1986 6983318000 1987 6579983000 1988 2960341000 1989 1086836000 1990 1139859000 1991 2159379000 1992 3272088000 1993 4281772000 1994 5601781000 1995 6832097000 1996 8454021000 1997 9636706000 1998 10107804000 1999 9110876000 2000 11259184000 2001 12740487000 2002 16781889000 2003 22739464000 2004 29689399000 2005 38884066000 2006 53980690000 2007 84381085000 2008 99447359000 2009 113615501000 2010 115392635000 2011 119601150000 2012 120825677000 2013 123953892000 2014 111824203000 2015 96448286000 2016 95888350000