Year US Dollars 1970 0 1971 0 1972 146504000 1973 497821000 1974 1257485000 1975 1680487000 1976 1993988000 1977 2331731000 1978 2820090000 1979 2967070000 1980 3802227000 1981 4209316000 1982 4940332000 1983 5346290000 1984 5541813000 1985 6530064000 1986 7913830000 1987 9737966000 1988 10275896000 1989 10701054000 1990 12291773000 1991 12997668000 1992 13427958000 1993 14125217000 1994 15490544000 1995 15734746000 1996 15169074000 1997 14257777000 1998 15509849000 1999 16452032000 2000 15602838000 2001 14981002000 2002 16689962000 2003 18442975000 2004 19716789000 2005 18505584000 2006 20162643000 2007 21574985000 2008 23407581000 2009 25437537000 2010 26880728000 2011 27276717000 2012 28558969000 2013 33994737000 2014 35662409000 2015 38688480000 2016 41125641000