Year US Dollars 1970 477531000 1971 497896000 1972 581162000 1973 844708000 1974 1152689000 1975 1290223000 1976 1493329000 1977 1658884000 1978 2173736000 1979 2720996000 1980 3386807000 1981 3228163000 1982 3367820000 1983 3628281000 1984 3511512000 1985 4181349000 1986 4603586000 1987 5783677000 1988 5809652000 1989 5889233000 1990 7055159000 1991 7453506000 1992 6898202000 1993 7111502000 1994 7124411000 1995 7309191000 1996 6813730000 1997 6465016000 1998 6824530000 1999 6526077000 2000 6148248000 2001 5496282000 2002 6097000000 2003 6716482000 2004 6916407000 2005 6486772000 2006 6681910000 2007 7538434000 2008 7659361000 2009 8549248000 2010 8847568000 2011 10162730000 2012 11893745000 2013 13836037000 2014 16969376000 2015 19764038000 2016 22324987000