Year	%
1985	26.3
1986	28.1
1987	29.5
1988	28.8
1989	30.8
1990	27.7
1991	27.2
1992	27.3
1993	27
1994	28.1
1995	28.3
1996	29
1997	29.6
1998	30.6
1999	30
2000	30.1
2001	30.9
2002	31
2003	30.2
2004	30.2
2005	30.8
2006	30.9
2007	31.1
2008	32.6
2009	31.2
2010	30.5
2011	32.1
2012	34.3
2013	32
2014	31.2
2015	32.9
2016	31.7
2017	34.5
2018	35.4
2019	34.2
2020	33.4
2021	32.7