Year	constant 2015 US$
1991	249650000
1992	334240000
1993	250230000
1994	150310000
1995	245060000
1996	97320000
1997	76070000
1998	54050000
1999	55120000
2000	72920000
2001	69460000
2002	65910000
2003	65830000
2004	69150000