Year	Percent
1991	28.58
1992	28.491
1993	28.079
1994	27.17
1995	25.848
1996	25.293
1997	24.817
1998	24.092
1999	23.464
2000	23.01
2001	22.575
2002	22.313
2003	22.225
2004	23.614
2005	24.591
2006	26.592
2007	26.611
2008	25.674
2009	24.982
2010	24.436
2011	24.226
2012	24.425
2013	25.13
2014	25.21
2015	25.013
2016	24.835
2017	24.764
2018	24.622
2019	24.474
2020	24.38
2021	24.343
2022	24.323