1952

0.0

1961

5.6

1968

6.4

1964

6.2

1966

6.3

1992

6.2

2007

5.7

2006

7.6

1960

6.6

1968

6.4

1975

6.3

1976

7.4

2001

6.8

1997

6.6

1994

6.9

1992

7.4

1964

6.2

2003

6.3

1964

6.3

2000

6.4