1955

6.0

1977

7.3

1960

7.5

1999

5.6

1970

4.5

1999

5.6

2002

6.7

1986

4.8

1997

6.8

2006

6.4

1986

8.0

2001

7.0

1969

3.8

1980

5.8

2002

7.1

1988

2.5

2001

6.2

1988

5.6

1996

6.8

1996

6.8