Year	Percent
1991	16.374
1992	16.397
1993	14.623
1994	15.408
1995	15.904
1996	15.875
1997	15.955
1998	15.535
1999	15.391
2000	16.213
2001	15.988
2002	16.08
2003	16.076
2004	15.863
2005	15.971
2006	16.506
2007	16.506
2008	16.207
2009	16.121
2010	16.428
2011	16.602
2012	16.793
2013	16.882
2014	16.964
2015	16.633
2016	16.75
2017	16.934
2018	17.072
2019	17.22
2020	17.393
2021	17.555
2022	17.728