Year	Percent
1991	45.301
1992	42.085
1993	38.862
1994	30.92
1995	31.184
1996	33.088
1997	32.684
1998	31.865
1999	29.142
2000	27.862
2001	26.995
2002	25.013
2003	25.714
2004	24.852
2005	23.126
2006	22.491
2007	24.106
2008	21.422
2009	18.617
2010	17.354
2011	15.018
2012	15.9
2013	16.165
2014	16.394
2015	17.994
2016	18.323
2017	19.42
2018	19.449
2019	19.061
2020	18.605
2021	18.133
2022	17.66