Year	Percent
1991	16.44
1992	16.3
1993	16.433
1994	15.801
1995	15.337
1996	15.174
1997	14.874
1998	14.491
1999	14.071
2000	13.71
2001	13.552
2002	13.498
2003	13.76
2004	13.72
2005	13.56
2006	13.345
2007	13.073
2008	12.939
2009	13.112
2010	13.164
2011	12.763
2012	12.54
2013	12.22
2014	12.095
2015	12.146
2016	12.078
2017	12.024
2018	11.94
2019	11.836
2020	11.772
2021	11.719
2022	11.667