Year	%
1983	28.4
1987	26.8
1990	31.1
1993	30.4
1999	28.1
2004	29.8
2005	29
2006	30
2007	29.6
2008	29.3
2009	27.9
2010	27.8
2011	27.8
2012	27.6
2013	28.1
2014	28.6
2015	28.2
2016	28.2
2017	28.5
2018	28.1
2019	29.2
2020	26
2021	25.7