Year	%
1985	34.9
1988	35.3
1992	34.5
1995	37.3
1997	36.1
2000	41.7
2003	37
2004	39.2
2005	38.2
2006	36.9
2007	38
2008	37.2
2009	37.2
2010	37.2
2011	36.8
2012	36.4
2013	36.4
2014	36.9
2015	36.5
2016	36.4
2017	36.3
2018	36.4
2019	36.5
2020	35.5
2021	36