Year	Percent
1991	13.193
1992	13.331
1993	13.822
1994	13.824
1995	14.075
1996	13.984
1997	14.327
1998	15.075
1999	14.501
2000	14.368
2001	14.87
2002	15.131
2003	15.217
2004	15.51
2005	15.509
2006	15.596
2007	15.303
2008	15.858
2009	15.665
2010	15.79
2011	15.723
2012	15.457
2013	16.011
2014	15.497
2015	15.516
2016	15.658
2017	15.745
2018	15.728
2019	15.802
2020	15.909
2021	16.005
2022	16.102