Year	%
1971	5.6
1973	6.3
1975	6.5
1977	6.6
1979	6.7
1981	7
1982	7
1984	6.8
1985	6.9
1986	7.3
1987	7.4
1988	7.6
1989	7.5
1990	7.3
1991	7.2
1992	7.4
1993	7.2
1994	7.4
1995	7.3
1996	7.3
1997	7.3
1998	7.2
1999	7.1
2000	7.1
2001	7.1
2002	7.1
2003	7
2004	7
2005	7.1
2006	7.1
2007	7.2
2008	7.1
2009	7
2010	7.2
2011	7.4
2012	6.9
2013	6.7
2014	7.1
2015	6.9
2016	7.3
2017	7.1
2018	7.4
2019	7.6