0.0
1988
7.0
1981
4.5
1969
5.9
1950
5.0
1959
6.0
1975
6.8
1999
7.2
1965
8.0
1970
1985
7.1
2015
1977
2013
2002
2009
8.5
1994
2008
2011
10.0
2012