1992

6.2

1982

6.7

1975

6.3

2001

7.8

1999

7.0

2006

5.3

1991

6.2

2002

5.7

1997

6.9

2002

5.3

2001

5.9

1996

6.4

1946

7.6

1968

7.1

1990

6.5

1973

6.9

2006

6.7

1979

7.2

1997

6.4

2002

6.7