Year	Percent
1991	54.471
1992	52.594
1993	50.29
1994	48.884
1995	47.586
1996	46.294
1997	44.872
1998	43.928
1999	42.583
2000	41.06
2001	39.781
2002	38.332
2003	36.377
2004	34.975
2005	32.809
2006	30.492
2007	28.224
2008	26.54
2009	24.865
2010	23.318
2011	21.664
2012	20.385
2013	19.205
2014	18.061
2015	16.99
2016	15.927
2017	15.177
2018	14.25
2019	13.424
2020	12.652
2021	11.941
2022	11.287