Year	%
1986	36.1
1989	39.8
1992	41.9
1996	36.5
1997	37.9
2000	40.2
2001	39.2
2002	38.3
2003	41.7
2004	41.7
2005	39
2006	41.2
2007	38.6
2008	37.8
2009	38.7
2010	36.5
2011	37.5
2012	36
2013	37.9
2014	33.4
2015	34.9
2016	35.4
2017	33.5
2018	35.2
2019	33.1
2020	30.4
2021	30.2
2022	28.3