Year	Percent
1991	8.912
1992	8.654
1993	8.41
1994	8.208
1995	7.659
1996	8.05
1997	8.393
1998	8.162
1999	7.913
2000	7.702
2001	8.079
2002	8.564
2003	9.211
2004	10.292
2005	9.639
2006	10.531
2007	10.496
2008	11.348
2009	11.636
2010	11.634
2011	12.94
2012	13.409
2013	14.135
2014	12.721
2015	12.69
2016	12.312
2017	12.463
2018	12.578
2019	12.675
2020	12.751
2021	12.779
2022	12.758
