Year	%
2000	35.8
2001	35.5
2002	34.8
2003	34.2
2004	34.1
2005	33.7
2006	32.4
2007	33.1
2008	31.8
2009	31.1
2010	30.2
2011	29.6
2012	29.7
2013	28.9
2014	28.8
2015	29.1
2016	28.6
2017	28.6
2018	28.6
2019	28.3