Year	Percent
1991	27.285
1992	27.2
1993	26.446
1994	26.114
1995	26.231
1996	26.107
1997	25.581
1998	24.94
1999	24.255
2000	23.914
2001	23.376
2002	22.898
2003	22.939
2004	26.633
2005	26.687
2006	24.427
2007	22.151
2008	21.148
2009	20.816
2010	20.158
2011	19.664
2012	19.417
2013	20.715
2014	21.1
2015	20.766
2016	20.543
2017	20.311
2018	20.182
2019	19.985
2020	19.779
2021	19.581
2022	19.375