Year US Dollars 1970 385063000 1971 395964000 1972 452075000 1973 564427000 1974 1136484000 1975 1598562000 1976 2087108000 1977 2620859000 1978 3159017000 1979 4077983000 1980 5176870000 1981 6193990000 1982 7169373000 1983 7506205000 1984 8480411000 1985 8955220000 1986 9631221000 1987 11248634000 1988 11530982000 1989 13359369000 1990 14798046000 1991 15298883000 1992 15558411000 1993 15979636000 1994 17096154000 1995 17816474000 1996 16971981000 1997 16326143000 1998 16843013000 1999 16203845000 2000 16076004000 2001 15030792000 2002 16130971000 2003 17297666000 2004 18335821000 2005 17563364000 2006 18453917000 2007 19743364000 2008 20291672000 2009 21067009000 2010 22286340000 2011 21148417000 2012 21796532000 2013 22471572000 2014 21762241000 2015 21403615000 2016 21082004000