Year	%
1997	11.4
1998	10.8
1999	10.1
2000	11.5
2001	11.1
2002	11.4
2003	11.8
2004	11.8
2005	11.5
2006	11.7
2007	11.9
2008	12
2009	12.2
2010	12.5
2011	12.9
2012	13.2
2013	13.4
2014	13.7
2015	13.7
2016	14.1
2017	14.1
2018	14.2
2019	14.1
2021	14.2