Year	Percent
1991	30.252
1992	25.656
1993	25.882
1994	27.375
1995	27.8
1996	28.456
1997	28.42
1998	28.469
1999	27.079
2000	26.239
2001	27.821
2002	27.563
2003	27.351
2004	26.174
2005	25.847
2006	24.729
2007	24.824
2008	24.352
2009	24.055
2010	23.142
2011	21.556
2012	22.102
2013	21.956
2014	19.771
2015	18.447
2016	17.788
2017	17.729
2018	17.556
2019	17.428
2020	17.332
2021	17.242
2022	17.174