Year	%
1990	32.2
1993	33.9
1996	35.2
1999	38.7
2002	42
2005	40.9
2008	43
2010	43.7
2011	42.4
2012	42.2
2013	39.7
2014	39.2
2015	38.6
2016	38.5
2017	39.1
2018	38.5
2019	38.2
2020	37.1