1981

7.2

1995

6.5

1961

8.1

2005

7.4

1990

7.3

2003

8.1

1994

7.3

1969

6.8

1983

0.0

2009

6.0

2014

6.2

1985

6.6

1978

6.7

1955

7.0

2006

6.6

1989

7.5

2006

6.5

2005

7.2

2000

6.0

2020

0.0