1936

4.0

1950

6.0

1997

6.4

1998

6.6

1998

7.1

1999

7.3

2001

6.9

2003

6.6

2005

4.4

2006

5.6

1967

6.0

2005

5.7

1989

6.1

2008

3.7

1981

6.8

1935

6.5

1969

3.6

2016

5.9

1979

7.3

2004

6.4