Year	Percent
1991	15.695
1992	15.82
1993	18.626
1994	18.758
1995	20.216
1996	21.131
1997	22.261
1998	22.41
1999	21.469
2000	23.415
2001	21.029
2002	20.819
2003	20.487
2004	19.429
2005	18.797
2006	17.125
2007	16.177
2008	15.448
2009	20.931
2010	21.002
2011	20.927
2012	20.585
2013	20.712
2014	16.458
2015	17.215
2016	16.619
2017	16.522
2018	16.043
2019	15.566
2020	15.174
2021	14.794
2022	14.424