Year	Percent
1977	17.71685
1978	16.04287
1979	17.33926
1980	16.47868
1981	17.13315
1982	14.27337
1983	13.43498
1984	12.99708
1985	11.06597
1986	11.08749
1987	12.29948
1988	11.68848
1989	10.26974
1990	8.88479
1991	8.9187
1992	7.78476
1993	7.43277
1994	7.11657
1995	7.17646
1996	6.00085
1997	5.58635
1998	5.2258
1999	5.37224
2000	5.16416
2001	5.3659
2002	6.29052
2003	5.86975
2004	5.01434
2005	2.96408
2006	3.89055
2007	3.55708
2008	3.76733
2009	4.62642
2010	4.51305
2011	4.44736
2012	4.8322
2013	4.83546
2014	6.10189
2015	7.42853
2016	6.20633
2017	5.37154
2018	5.20544
2019	4.67951
2020	4.90308
2021	5.33785
2022	4.14929