1979

7.7

1977

7.7

1973

7.4

2004

8.1

1994

8.3

1976

8.1

1961

7.7

1999

7.2

2007

6.2

2007

6.1

2000

7.4

2006

6.3

1989

10.0

2003

5.8

2002

7.3

1991

6.2

1990

6.7

2005

6.2

2003

6.4

2015

7.2