Year	Percent
1991	45.311
1992	42.874
1993	42.343
1994	42.99
1995	40.781
1996	39.745
1997	37.856
1998	36.589
1999	34.627
2000	32.988
2001	34.36
2002	35.211
2003	35.111
2004	33.773
2005	31.853
2006	28.534
2007	25.211
2008	23.182
2009	27.828
2010	32.912
2011	29.284
2012	28.036
2013	31.944
2014	28.408
2015	24.943
2016	21.975
2017	22.118
2018	21.945
2019	21.476
2020	20.949
2021	20.427
2022	19.943