1993

6.3

1991

6.7

2003

7.1

2002

6.2

1997

6.8

2005

6.7

1984

6.3

2005

7.0

1992

6.8

2005

6.2

2007

6.5

2008

6.5

1974

7.5

1965

7.4

2014

5.4

1958

6.6

1997

7.3

2012

4.3

2002

7.3

1971

6.8