Year	U.S. dollars (Billions)
1980	-0.635
1981	-0.466
1982	-0.252
1983	-0.807
1984	-0.797
1985	-0.859
1986	-0.504
1987	-0.298
1988	-0.131
1989	1.222
1990	1.748
1991	1.685
1992	0.542
1993	-0.242
1994	-0.852
1995	0.207
1996	-0.041
1997	0.412
1998	0.130
1999	0.303
2000	1.036
2001	0.830
2002	1.120
2003	-1.663
2004	-0.781
2005	-0.648
2006	0.480
2007	-0.095
2008	-0.673
2009	-1.584
2010	-1.707