Year	%
1997	2.4
1998	2.4
1999	2.4
2000	2.5
2001	2.6
2002	2.6
2003	2.4
2004	2.3
2005	2.3
2006	2.3
2007	2.3
2008	2.4
2009	2.6
2010	2.5
2011	2.6
2012	2.5
2013	2.6
2014	2.6
2015	2.8
2016	2.8
2017	2.9
2018	2.9
2019	2.9
2020	3.1