Year	%
1985	14.1
1986	13.5
1987	13.2
1988	13.3
1989	13
1990	13.7
1991	13.8
1992	13.8
1993	13.7
1994	13.6
1995	13.6
1996	13.5
1997	13.3
1998	12.9
1999	13.1
2000	13
2001	12.9
2002	12.8
2003	13.1
2004	13.2
2005	13
2006	12.9
2007	12.9
2008	12.6
2009	12.7
2010	12.9
2011	12.4
2012	11.8
2013	12.5
2014	12.9
2015	12.3
2016	12.7
2017	11.9
2018	11.9
2019	11.9
2020	12.3
2021	12.3