Year	Percent
1970	19.50836
1971	19.84481
1972	19.25239
1973	20.12108
1974	21.24637
1975	20.84459
1976	20.6139
1977	20.17776
1978	18.49552
1979	18.05011
1980	16.94894
1981	17.27903
1982	16.08618
1983	19.45813
1984	21.54583
1985	19.01563
1986	16.93318
1987	16.29615
1988	15.73538
1989	15.26314
1990	15.3536
1991	15.5421
1992	14.4042
1993	14.64796
1994	15.24429
1995	14.8593
1996	14.18468
1997	14.91826
1998	12.62543
1999	13.25799
2000	12.96581
2001	13.25565
2002	12.95512
2003	13.42724
2004	13.32238
2005	11.79272
2006	10.93755
2007	10.01116
2008	10.4424
2009	11.15241
2010	10.38991
2011	9.76959
2012	9.81216
2013	9.96698
2014	9.74022
2015	10.23949
2016	11.17188
2017	11.58934
2018	11.48192
2019	12.22176
2020	14.00093
2021	12.92292
2022	12.46873