1961

7.3

1963

7.0

1964

7.0

1990

8.5

1995

6.6

1996

8.0

1997

7.4

1971

8.2

1983

7.2

1986

7.8

1972

8.7

1974

8.6

2005

6.7

1996

7.7

2007

7.9

2003

5.8

2006

7.4

2002

7.3

1960

7.6

1948

7.6