Year	Percent
1991	13.565
1992	13.45
1993	14.511
1994	15.238
1995	15.837
1996	16.242
1997	16.071
1998	15.588
1999	17.511
2000	17.105
2001	14.621
2002	13.647
2003	13.443
2004	12.364
2005	12.293
2006	12.148
2007	11.003
2008	10.488
2009	10.406
2010	9.852
2011	9.617
2012	9.169
2013	8.511
2014	8.221
2015	8.223
2016	8.326
2017	8.312
2018	8.195
2019	8.09
2020	7.99
2021	7.889
2022	7.78