Year	Change
1971	2.9
1972	3.1
1973	-1.2
1974	-1.1
1975	-3.3
1976	3.7
1977	1.9
1978	-0.3
1979	-5.9
1980	-7.9
1981	-5.5
1982	-7.2
1983	-4.1
1984	-8.6
1985	-5.5
1986	-0.7
1987	-5.1
1988	-7.1
1989	-4.2
1990	0.9
1991	-6.1
1992	-4.1
1993	-4.8
1994	-11.3
1995	-9.3
1996	-10.7
1997	-1.8
1998	-7.4
1999	-22.9