Year	%
1980	41.7
1985	42.1
1990	39.9
1993	42.4
1994	41.8
1995	42.5
1996	42.8
1997	42
1998	41.4
1999	41.2
2000	41.3
2003	39.1
2004	40.3
2005	39.6
2006	40.4
2007	41
2008	41
2009	41.5
2010	41.7
2011	41.8
2012	41.6
2013	41.9
2014	41.9
2015	42.1
2016	41.7
2017	41
2018	41
2019	40.6
2020	41
2021	40.4