1961

7.7

2001

6.4

1988

6.2

1971

7.2

2009

5.4

2001

6.2

1986

7.6

1922

7.2

1983

6.8

2008

6.1

1990

6.7

2010

7.2

2000

5.5

1967

6.6

2006

7.0

1999

7.5

1985

6.3

1979

6.7

2003

5.5

2010

5.8