Year	%
1986	36.9
1990	33.5
1994	33.3
1998	33.7
2005	33.3
2006	34
2009	31.3
2011	26.7
2012	26.9
2013	26.7
2014	27.1
2015	27.6
2016	28.1
2017	28.3
2018	29.1
2019	28.3
2020	27.6
2021	27.2
2022	26.8