Year	Percent
1980	23.00885
1981	23.57724
1982	21.53846
1983	21.9697
1984	24.28571
1985	24.28571
1986	24.81752
1987	22.53521
1988	22.60274
1989	21.52778
1990	30
1991	26.5625
1992	52.34584
1996	33.15238
1997	27.50664
1998	26.244
1999	24.72172
2000	20.60201
2001	20.96194
2002	19.24088
2003	19.3015
2004	16.39506
2005	14.76994
2006	11.19878
2007	9.19571
2008	8.13163
2009	8.1013
2010	8.4508
2011	9.13194
2012	8.17562
2013	8.61641
2014	8.52622
2015	7.81376
2016	7.29657
2017	6.24019
2018	6.7622
2019	6.50459
2020	7.28867
2021	6.46633
2022	5.96846