Year	Percent
1991	18.145
1992	18.245
1993	18.684
1994	18.567
1995	18.589
1996	22.776
1997	24.495
1998	20.914
1999	21.012
2000	21.081
2001	20.796
2002	21.608
2003	21.447
2004	21.71
2005	17.966
2006	18.245
2007	18.061
2008	18.262
2009	17.425
2010	17.37
2011	17.284
2012	17.147
2013	16.78
2014	16.572
2015	16.31
2016	16.69
2017	17.075
2018	17.124
2019	17.043
2020	16.943
2021	16.824
2022	16.714