1999

5.4

2002

6.7

1996

5.6

1969

7.0

1994

5.7

1973

6.4

1973

7.5

2005

5.7

1989

6.3

1987

6.0

2001

6.0

2005

6.0

2000

6.1

1983

6.5

1977

6.0

2000

5.1

1982

6.0

2006

6.1

1986

7.0

2002

6.2