1983

8.2

1994

4.6

1964

7.4

2002

5.4

2006

5.9

1977

7.1

1991

6.4

1998

5.5

1995

6.5

1999

7.3

2001

6.0

1988

6.3

2011

6.1

1990

6.0

1969

7.0

1988

6.8

1999

5.7

1997

5.0

1993

7.5

2011

2.0