Year	%
1981	49.2
1989	48.1
1992	47.4
1995	46.8
1996	46.8
1997	47.4
1998	48.1
2000	48.6
2001	50.4
2002	50.9
2003	50.8
2004	51.2
2005	50.2
2006	51.6
2007	51.9
2008	50.8
2009	51
2010	50.1
2011	48
2012	45.8
2013	46.4
2014	46.1
2015	46.1
2016	45.8
2017	45.7
2018	45.9
2019	45.9
2020	46.2
2021	46.8
2022	46.7