1997

6.5

2000

6.4

2003

6.1

2004

3.7

1997

6.6

2001

6.3

1996

7.2

1959

6.0

1999

6.4

2007

6.7

2017

6.0

1970

4.2

1960

5.0

1973

4.0

1971

7.1

1964

6.2

1976

6.0

2003

5.5

2001

6.3

2004

5.3