1991

4.6

2006

6.6

2014

4.8

2018

4.6

1973

6.8

1995

5.4

1994

5.7

1971

5.2

1933

5.8

1987

5.2

2009

6.5

1978

7.6

1996

6.9

1971

7.3

2003

5.6

2012

5.8

1997

6.6

1969

7.6

1983

6.7

2000

6.8