Year	Percent
1991	16.773
1992	16.716
1993	16.843
1994	17.583
1995	17.263
1996	16.731
1997	16.261
1998	16.339
1999	16.465
2000	16.698
2001	16.843
2002	15.844
2003	15.95
2004	14.489
2005	13.414
2006	14.283
2007	15.578
2008	16.117
2009	16.323
2010	18.22
2011	19.532
2012	20.593
2013	18.061
2014	16.154
2015	14.698
2016	14.695
2017	14.542
2018	14.625
2019	14.815
2020	15.045
2021	15.25
2022	15.458