Year US Dollars 1970 1801616000 1971 2049120000 1972 1952426000 1973 1991612000 1974 2209482000 1975 4835412000 1976 6357335000 1977 11733543000 1978 12857845000 1979 14905846000 1980 19130728000 1981 22077856000 1982 27323625000 1983 30213009000 1984 32187452000 1985 36124648000 1986 39891261000 1987 44151537000 1988 46148552000 1989 45676108000 1990 33015763000 1991 32604278000 1992 31168992000 1993 30651246000 1994 32499135000 1995 33475211000 1996 31512675000 1997 29952923000 1998 32297027000 1999 31079798000 2000 29195236000 2001 28297377000 2002 29632235000 2003 30421582000 2004 31358191000 2005 30538145000 2006 30984860000 2007 34551447000 2008 33892718000 2009 35415768000 2010 36833666000 2011 35236442000 2012 40089690000 2013 46562030000 2014 41826538000 2015 48459014000 2016 67214081000