Year	Percent
1991	8.082
1992	8.444
1993	8.229
1994	8.828
1995	10.242
1996	10.317
1997	8.003
1998	9.039
1999	9.714
2000	9.976
2001	10.386
2002	10.496
2003	11.729
2004	11.076
2005	10.432
2006	10.885
2007	10.578
2008	10.646
2009	11.421
2010	12.189
2011	12.911
2012	13.464
2013	13.545
2014	12.872
2015	12.803
2016	13.254
2017	13.567
2018	13.45
2019	13.408
2020	13.401
2021	13.402
2022	13.394