1992

7.4

1999

7.7

1986

7.6

2006

7.0

1997

7.6

1989

8.4

1989

5.7

1963

6.0

1998

6.5

1993

6.7

1995

6.6

2007

6.1

1990

6.1

1994

5.6

1980

5.3

1967

5.5

1983

5.6

1991

4.3

1991

5.0

2013

6.5