1952

6.7

1990

6.1

1981

6.5

1985

5.8

2005

6.6

1989

7.0

1987

7.3

2002

6.3

1974

6.5

1986

6.8

2012

6.0

1988

6.2

2017

6.8

1992

6.9

1987

6.8

1994

4.5

1997

6.4

1925

7.6

1978

5.0

2003

8.5