1981

5.1

1982

5.2

2001

7.0

1998

6.0

1961

6.9

1995

5.2

2009

7.8

2010

5.3

1993

6.5

2010

6.4

1988

6.2

1982

6.7

1988

6.1

1956

7.7

2002

4.6

2011

6.8

2012

5.8

1994

6.6

2005

5.2

1988

6.5