Year	%
1979	3.9
1986	4.3
1991	4.1
1995	3.9
2000	4
2003	3.8
2004	3.5
2005	3.5
2006	3.5
2007	3.6
2008	3.5
2009	3.7
2010	3.7
2011	3.8
2012	3.7
2013	3.7
2014	3.5
2015	3.5
2016	3.2
2017	3.3
2018	3.4
2019	3.4