Year	%
1985	4
1986	3.8
1987	3.8
1988	3.9
1989	3.9
1990	4
1991	3.9
1992	4
1993	4.1
1994	3.7
1995	3.7
1996	3.5
1997	3.5
1998	3.4
1999	3.4
2000	3.5
2001	3.4
2002	3.6
2003	3.3
2004	3.3
2005	3.3
2006	3.3
2007	3.3
2008	3.2
2009	3.3
2010	3.3
2011	3.2
2012	3
2013	3.1
2014	3.2
2015	2.9
2016	2.9
2017	2.5
2018	2.5
2019	2.8
2020	2.8
2021	2.8