Year	%
1981	51.4
1988	50.7
1990	52.2
1992	54.4
1994	50.4
1996	49.9
1998	48.5
1999	50.1
2000	49.7
2002	48.9
2004	49.3
2006	48.5
2007	46.7
2008	47.2
2009	46.5
2010	46.5
2011	45.1
2012	46.3
2013	45.1
2014	44.5
2015	43.8
2016	44.5
2017	43.9
2018	44
2019	42.8
2020	42.7
2021	42.7