Year	%
1979	21.8
1986	20.5
1991	21.2
1995	21.7
2000	23.2
2003	23.3
2004	27.2
2005	26.3
2006	21.2
2007	22.2
2008	21.8
2009	21.3
2010	21
2011	20.5
2012	20.9
2013	21.3
2014	21.6
2015	22.3
2016	23.1
2017	21.6
2018	22.2
2019	22.4