Year	Percent
1980	18.56005
1981	15.77265
1982	12.58012
1983	12.05682
1984	11.85649
1985	12.98961
1986	13.63127
1987	17.64634
1988	17.69673
1989	16.21087
1990	14.3907
1991	13.39301
1992	11.7942
1993	10.13643
1994	12.85895
1995	13.68057
1996	12.44848
1997	11.68065
1998	10.94725
1999	13.64337
2000	12.87178
2001	11.41577
2002	10.35147
2003	10.1437
2004	9.86347
2005	9.00119
2006	8.31871
2007	6.09469
2008	5.31578
2009	6.02632
2010	5.82909
2011	5.39925
2012	5.79089
2013	5.82359
2014	5.73507
2015	6.40829
2016	6.31352
2017	5.37534
2018	4.52277
2019	4.43736
2020	6.19133
2021	6.11726
2022	4.82105