Year	%
2000	41.5
2001	40.2
2002	39.1
2003	39.8
2004	37.9
2005	37.6
2006	36.3
2007	35.6
2008	33.3
2009	31.2
2010	31.4
2011	30.4
2012	29.2
2013	27.3
2014	26.3
2015	25.6
2016	24.8
2017	24.1
2018	23.1
2019	22.4