Year	%
1991	23.2
1992	23.1
1993	22.8
1994	22.9
1995	22.7
1996	22.3
1997	22.4
1998	22.3
1999	23.1
2000	22.9
2001	23.9
2002	23.7
2003	23.9
2004	24
2005	25.1
2006	24.7
2007	25.1
2008	24.7
2009	24
2010	24
2011	24.5
2012	24.4
2013	25
2014	24.1
2015	24.8
2016	24.6
2017	24.8
2018	25.2
2019	25.2