Year	Percent
1971	5.98384
1972	6.86704
1973	7.76504
1974	11.36297
1975	13.64989
1976	10.80857
1977	8.80683
1978	9.15878
1979	10.10257
1980	11.25732
1981	11.44263
1982	11.99148
1983	9.51516
1984	7.27708
1985	5.52667
1986	5.27888
1987	2.78045
1988	3.07278
1989	3.30839
1990	2.64056
1991	2.53982
1992	2.13588
1993	1.55003
1994	1.34566
1995	1.30791
1996	1.60458
1997	1.01405
1998	0.90092
1999	0.04625
2000	1.40062
2001	1.6489
2002	2.38017
2003	1.87868
2004	1.58979
2005	2.03425
2006	2.82071
2007	2.47789
2008	-1.62485