Year	Percent
1971	0.59439
1972	0.60201
1978	0.62272
1979	0.63161
1980	0.63316
1981	0.6334
1982	0.63522
1983	0.637
1984	0.63942
1985	0.64592
1986	0.64678
1988	0.66245
1989	0.66812
1990	0.6786
1992	0.69734
1996	0.75553
1997	0.7725
1998	0.79384
1999	0.78633
2000	0.82073
2001	0.83814
2002	0.85163
2004	0.89528
2005	0.90997
2006	0.92639
2008	0.95534
2010	0.99601
2011	1.04938
2012	1.05048
2013	1.06225
2014	1.07355
2015	1.06537
2016	1.08037