Year	Percent
1991	23.889
1992	22.574
1993	22.942
1994	22.62
1995	21.156
1996	19.566
1997	19.528
1998	20.953
1999	19.199
2000	21.214
2001	21.242
2002	21.267
2003	20.973
2004	21.446
2005	21.709
2006	22.563
2007	22.795
2008	24.255
2009	23.036
2010	22.288
2011	22.925
2012	22.162
2013	21.5
2014	21.36
2015	20.967
2016	19.177
2017	19.122
2018	19.472
2019	19.404
2020	19.373
2021	19.458
2022	19.511