Year	%
1979	42.8
1986	43
1992	42.4
1997	44.3
2001	44.9
2002	45.1
2003	45.9
2004	46.2
2005	47.2
2006	46.4
2007	46.1
2008	46.5
2009	47
2010	47.3
2011	46.2
2012	46
2013	45
2014	44.8
2015	44.8
2016	44.2
2017	43.3
2018	43.8
2019	43.5
2020	43.2
2021	43.3