Year	Percent
1991	9.084
1992	9.15
1993	9.371
1994	9.57
1995	9.602
1996	9.762
1997	9.947
1998	9.819
1999	15.21
2000	15.146
2001	15.545
2002	15.352
2003	15.337
2004	14.863
2005	14.819
2006	14.582
2007	14.211
2008	13.583
2009	13.737
2010	13.766
2011	19.78
2012	19.205
2013	19.919
2014	20.297
2015	19.815
2016	19.914
2017	19.789
2018	20.043
2019	20.276
2020	20.527
2021	20.743
2022	20.87