Year	%
1987	21.6
1992	20.5
1995	19.8
2000	20.1
2003	21.4
2004	20.7
2005	21
2006	21.8
2007	22.1
2008	21
2009	21.8
2010	22.5
2011	22.7
2012	23.1
2013	23.7
2014	23.6
2015	23.8
2016	23.7
2017	24
2018	23.5
2019	23.5
2020	22.9
2021	23.8