Year	Percent
1991	18.059
1992	16.955
1993	16.33
1994	20.069
1995	19.775
1996	19.902
1997	15.954
1998	14.801
1999	14.903
2000	15.674
2001	14.24
2002	14.597
2003	15.654
2004	15.481
2005	14.488
2006	13.708
2007	13.138
2008	12.749
2009	13.917
2010	13.747
2011	12.547
2012	12.21
2013	11.479
2014	11.999
2015	13.435
2016	13.46
2017	14.315
2018	14.476
2019	14.311
2020	13.936
2021	13.669
2022	13.433