1953

7.2

1998

6.0

1991

6.2

2013

6.7

1993

6.1

1971

6.0

1988

6.5

1989

5.5

2020

6.5

2005

7.8

1980

5.9

2006

6.7

2009

7.7

2014

7.0

1998

6.5

1992

5.7

1975

6.4

2006

6.8

1958

5.6

2001

7.9