Year	Percent
1960	57.47431
1961	57.98824
1962	57.01857
1963	57.14667
1964	53.35684
1965	52.81869
1966	53.94737
1967	55.85248
1968	53.55574
1969	55.41282
1970	54.5615
1971	51.03131
1972	59.60991
1973	56.63885
1974	56.63655
1975	61.95414
1976	51.91446
1977	48.89806
1978	54.25031
1979	52.45201
1980	32.82389
1981	31.95152
1982	31.4417
1983	31.04603
1984	34.69863
1985	33.00673
1986	32.36915
1987	32.6639
1988	31.31918
1989	30.56164
1990	30.48983
1991	31.67702
1992	30.51753
1993	27.32109
1994	26.72554
1995	27.30437
1996	23.26621
1997	23.24614
1998	22.58742
1999	22.65841
2000	22.71815
2001	21.84834
2002	20.58413
2003	19.81272
2004	19.26696
2005	18.57104
2006	18.03402
2007	17.80654
2008	17.5957
2009	17.10463
2010	17.00118
2011	16.80999
2012	16.17756
2013	15.49328
2014	15.35162
2015	14.783
2016	13.46479
2017	12.95728
2018	12.48008
2019	11.97532
2020	11.99969
2021	11.63286
2022	11.2176