Year	%
1987	54.4
1994	57.9
1995	56.1
1998	54.8
1999	62.5
2000	60.7
2003	58.1
2004	58.3
2005	57.5
2006	57
2007	58
2008	54.6
2009	53.5
2010	53.9
2011	51
2012	51.1
2013	52.2
2014	50.6
2015	51.3
2016	50.5
2017	50.1
2018	51
2019	51
2020	52.3
2021	51.3
2022	50.9