Year	Percent
1960	1.22432
1961	1.28898
1962	1.35727
1963	1.42895
1964	1.50378
1965	1.58103
1966	1.66102
1967	1.74377
1968	1.82984
1969	1.93738
1970	2.05124
1971	2.17151
1972	2.29859
1973	2.43189
1974	2.57218
1975	2.71929
1976	2.90621
1977	3.12886
1978	3.36667
1979	3.61918
1980	3.88694
1981	4.16885
1982	4.46746
1983	4.78402
1984	5.12161
1985	5.48062
1986	5.70238
1987	5.8007
1988	5.90012
1989	5.99945
1990	6.09964
1991	6.2004
1992	6.30217
1993	6.4038
1994	6.50629
1995	6.60921
1996	6.71287
1997	6.93085
1998	7.25102
1999	7.5845
2000	7.93257
2001	8.29353
2002	8.67031
2003	9.06217
2004	9.46994
2005	9.89092
2006	10.32859
2007	10.62478
2008	10.80185
2009	10.98029
2010	11.1632
2011	11.35033
2012	11.54268
2013	11.73864
2014	11.94102
2015	12.1496
2016	12.36479
2017	12.5869