Year	%
1971	85.19255
1972	84.82334
1973	84.45645
1974	82.5066
1976	80.34599
1977	79.89315
1978	80.09066
1979	79.56712
1980	79.98833
1981	80.03264
1982	80.5345
1983	81.15784
1984	80.35537
1985	78.37746
1986	74.74418
1987	71.50405
1988	69.58871
1989	66.69288
1990	65.7071
1991	65.89245
1992	63.49668
1993	64.01948
1998	68.78136
1999	68.59911
2000	71.30073
2001	72.26384
2002	100
2003	98.26798
2004	98.34874
2005	98.81711
2006	98.20983
2007	98.68291
2008	98.1459
2009	97.78559
2010	98.27506
2011	97.8
2012	57.31752