Year US Dollars 1970 836678000 1971 960363000 1972 1081762000 1973 1778978000 1974 1880719000 1975 1687172000 1976 1337792000 1977 3146444000 1978 5091172000 1979 6244581000 1980 8938206000 1981 11445508000 1982 11992472000 1983 17576994000 1984 17783310000 1985 18655380000 1986 22215776000 1987 29024888000 1988 29624122000 1989 30121999000 1990 33458490000 1991 33526926000 1992 29018674000 1993 30699253000 1994 33092286000 1995 34094442000 1996 31414751000 1997 28467541000 1998 30313711000 1999 29095542000 2000 32374086000 2001 31418236000 2002 31780095000 2003 36711576000 2004 39898101000 2005 25754638000 2006 9617378000 2007 12144519000 2008 13128901000 2009 15942066000 2010 15484219000 2011 17663308000 2012 18127298000 2013 21143713000 2014 24755955000 2015 28942968000 2016 31151475000