Year	Percent
1991	27.702
1992	27.467
1993	26.7
1994	25.832
1995	25.092
1996	24.679
1997	24.249
1998	22.773
1999	22.15
2000	21.57
2001	20.77
2002	19.758
2003	19.361
2004	18.434
2005	17.4
2006	17.225
2007	17.559
2008	16.54
2009	15.361
2010	14.944
2011	14.518
2012	14.703
2013	14.685
2014	14.48
2015	14.772
2016	14.544
2017	14.543
2018	14.236
2019	14.122
2020	13.983
2021	13.912
2022	13.766