Year	%
1981	43.6
1989	42.4
1992	41.5
1995	40.9
1996	40.8
1997	41.5
1998	42.5
2000	42.9
2001	45
2002	45.5
2003	45
2004	45.9
2005	44.7
2006	45.9
2007	46.4
2008	45.1
2009	45.5
2010	44.5
2011	42.2
2012	39.9
2013	40.5
2014	40.1
2015	40.1
2016	39.7
2017	39.5
2018	39.7
2019	39.7
2020	40.2
2021	40.8
2022	40.6