Year constant 2015 US$ 1985 33630000 1986 83190000 1987 35830000 1988 31830000 1989 42480000 1990 44230000 1991 36710000 1992 40450000 1993 34820000 1994 24530000 1995 30070000 1996 23560000 1997 34020000 1998 15230000 1999 -10240000