Year	%
1985	36
1986	37.3
1987	38.4
1988	38
1989	40.1
1990	37.2
1991	36.6
1992	36.8
1993	36.8
1994	37.2
1995	37.4
1996	37.8
1997	38.2
1998	39
1999	38.5
2000	38.7
2001	39.5
2002	39.7
2003	38.6
2004	38.7
2005	39.4
2006	39.4
2007	39.7
2008	40.8
2009	39.2
2010	38.8
2011	39.9
2012	41.7
2013	39.7
2014	39.1
2015	40.4
2016	39.4
2017	41.4
2018	42.2
2019	41.4
2020	40.5
2021	40