Year	%
1980	22.6
1986	21.8
1987	21.5
1991	20.3
1992	21.5
1993	22
1994	21.6
1995	20.8
1996	21.2
1997	21.3
1998	21
1999	21.3
2000	21.3
2001	21.1
2002	20.3
2003	21.5
2004	22.1
2005	22.1
2006	22.5
2007	22.4
2008	22.7
2009	23
2010	22.6
2011	22.7
2012	23.2
2013	23.3
2014	23.1
2016	22.8
2017	23
2018	23
2019	22.8
2020	23.2
2021	22.5
2022	22.7