Year	%
1987	50.5
1994	53.4
1995	51
1998	49.7
1999	58.6
2000	56.4
2003	53.5
2004	53.9
2005	53.1
2006	52.3
2007	53.4
2008	49.8
2009	48.5
2010	48.8
2011	45.9
2012	46.1
2013	46.9
2014	45
2015	46
2016	45
2017	44.7
2018	45.4
2019	45.7
2020	47.3
2021	45.8
2022	45.5