Year	Percent
1991	36.129
1992	34.33
1993	33.588
1994	29.981
1995	28.643
1996	26.437
1997	24.68
1998	22.507
1999	20.91
2000	21.02
2001	20.489
2002	18.949
2003	17.541
2004	17.693
2005	16.02
2006	17.628
2007	17.981
2008	15.49
2009	16.983
2010	14.992
2011	14.084
2012	13.885
2013	12.858
2014	11.389
2015	10.979
2016	10.697
2017	9.624
2018	8.736
2019	8.186
2020	7.628
2021	7.147
2022	6.761