Year	Percent
1991	41.626
1992	38.818
1993	39.628
1994	44.978
1995	43.268
1996	40.131
1997	44.66
1998	44.679
1999	45.941
2000	46.124
2001	46.114
2002	45.752
2003	44.656
2004	43.066
2005	39.872
2006	39.833
2007	38.34
2008	34.691
2009	33.231
2010	32.026
2011	30.947
2012	30.049
2013	29.154
2014	28.449
2015	27.293
2016	26.233
2017	26.118
2018	25.532
2019	24.755
2020	24.147
2021	23.554
2022	22.92