Year US Dollars 1970 0 1971 0 1972 0 1973 0 1974 0 1975 0 1976 0 1977 0 1978 0 1979 0 1980 0 1981 25579000 1982 42766000 1983 52564000 1984 54570000 1985 61267000 1986 174639000 1987 191481000 1988 617485000 1989 20705350000 1990 23270059000 1991 23395042000 1992 24331839000 1993 24167607000 1994 24799403000 1995 25427802000 1996 26255068000 1997 21776508000 1998 22457989000 1999 23274460000 2000 12785239000 2001 12578501000 2002 13267121000 2003 15517154000 2004 17565787000 2005 18530479000 2006 18686347000 2007 23070521000 2008 26435435000 2009 32702629000 2010 44901572000 2011 53886305000 2012 61576671000 2013 65452000000 2014 72429832000 2015 77827377000 2016 86952492000