Year	Percent
1991	16.653
1992	16.716
1993	15.144
1994	15.083
1995	14.966
1996	14.274
1997	14.319
1998	14.223
1999	14.283
2000	13.963
2001	13.85
2002	13.247
2003	12.302
2004	12.416
2005	11.971
2006	11.616
2007	11.43
2008	10.85
2009	10.205
2010	10.061
2011	10.441
2012	10.164
2013	10.034
2014	9.592
2015	9.296
2016	9.17
2017	9.275
2018	9.185
2019	9.109
2020	9.027
2021	8.949
2022	8.887