Year US Dollars 1970 939559000 1971 1260811000 1972 1549797000 1973 2991380000 1974 3365978000 1975 4632813000 1976 6114380000 1977 10598950000 1978 15733603000 1979 18505558000 1980 19363274000 1981 18370310000 1982 17639482000 1983 16367460000 1984 15890301000 1985 18260736000 1986 22649742000 1987 24448828000 1988 26101338000 1989 27248507000 1990 28153909000 1991 28489963000 1992 27351236000 1993 26274671000 1994 30241912000 1995 33051440000 1996 33653884000 1997 30902557000 1998 30692715000 1999 28206747000 2000 25476934000 2001 22763886000 2002 23045302000 2003 23774850000 2004 22426650000 2005 17092402000 2006 5910801000 2007 6134509000 2008 6246392000 2009 7420897000 2010 7260316000 2011 6064669000 2012 5515626000 2013 5245583000 2014 5521298000 2015 4671372000 2016 5466348000