Year	%
1989	25.5
1990	25.7
1991	22.1
1992	21
1993	20.9
1994	23.2
1995	23.5
1996	25
1997	23.3
1998	27
1999	26
2001	28
2002	26.1
2003	27.1
2004	27.2
2005	28.2
2006	28.1
2007	25
2008	26.1
2009	25
2010	24.5
2011	24.9
2012	25.6
2013	23.9
2014	24.8
2015	24
2016	25.9
2017	24.7
2018	24.5
2019	25.1