Year	%
1996	16.8
1997	19
1998	17.7
1999	18
2000	17
2001	15.3
2002	14.7
2003	15.4
2004	15.7
2005	15.5
2006	14.8
2007	15.4
2008	15.9
2009	15.1
2010	17.2
2011	16.9
2012	16.8
2013	15.6
2014	15.1
2015	13.4
2016	14
2017	14.8
2018	14.6
2019	13.8
2020	14
2021	13.5