Year	%
1987	22.3
1994	21.7
1995	21.9
1996	22
2000	22.2
2002	22.6
2003	22.3
2004	22.3
2005	21.9
2006	22.5
2007	22.3
2008	22.6
2009	22.3
2010	22.5
2011	22.5
2012	22.3
2013	22.2
2014	22.5
2015	22.1
2016	22
2017	22
2018	21.9
2019	22.1
2020	22.3
2021	21.9