Year	Percent
1991	16.773
1992	16.471
1993	15.115
1994	14.399
1995	13.972
1996	13.618
1997	13.663
1998	13.75
1999	13.492
2000	14.443
2001	14.369
2002	14.314
2003	13.311
2004	12.782
2005	12.419
2006	11.625
2007	11.603
2008	11.21
2009	10.06
2010	9.534
2011	8.888
2012	9.04
2013	8.464
2014	8.426
2015	8.666
2016	8.423
2017	8.331
2018	8.159
2019	7.988
2020	7.847
2021	7.716
2022	7.631