Year	Percent
1991	25.275
1992	24.682
1993	24.467
1994	23.833
1995	23.19
1996	22.201
1997	20.688
1998	19.747
1999	17.892
2000	16.73
2001	16.539
2002	15.114
2003	14.376
2004	14.143
2005	14.256
2006	13.647
2007	13.344
2008	13.179
2009	12.637
2010	12.297
2011	12.207
2012	12.755
2013	13.092
2014	12.989
2015	12.841
2016	12.751
2017	12.721
2018	12.596
2019	12.491
2020	12.415
2021	12.352
2022	12.306