Year	Percent
1971	14.3
1972	18.99
1973	-14.69
1974	-26.47
1975	37.23
1976	23.93
1977	-7.16
1978	6.57
1979	18.61
1980	32.5
1981	-4.92
1982	21.55
1983	22.56
1984	6.27
1985	31.73
1986	18.67
1987	5.25
1988	16.61
1989	31.69
1990	-3.1
1991	3.05
1992	7.62
1993	10.08
1994	1.32
1995	37.58
1996	22.96
1997	33.36
1998	28.58
1999	21.04
2000	-9.1
2001	-11.89
2002	-22.09
2003	28.67
2004	10.88
2005	4.91
2006	15.79
2007	5.49
2008	-37
2009	26.46
2010	14.87
2011	2.05