Year	%
1985	25.2
1988	25.7
1992	25
1995	28.4
1997	26.8
2000	33.1
2003	28.1
2004	30.5
2005	29.3
2006	28.1
2007	29.2
2008	28.4
2009	28.6
2010	28.4
2011	28.1
2012	27.5
2013	27.7
2014	28.1
2015	27.7
2016	27.6
2017	27.4
2018	27.2
2019	27.2
2020	26
2021	26.6