1990

6.1

1992

5.3

2009

6.2

2007

6.9

1971

7.0

1998

6.9

1988

6.2

1990

5.5

1985

6.4

1987

5.3

1990

5.9

2016

4.2

2011

6.5

2010

6.7

2002

6.3

1990

6.1

2008

7.5

1980

6.0

1999

8.0

1949

7.1