1970

5.6

2002

4.6

2008

6.1

2003

7.2

1999

6.6

2007

7.2

1998

7.5

1992

6.6

1983

7.4

2002

6.2

1995

6.2

2002

6.6

1994

5.2

2016

6.1

1988

5.0

1997

6.3

1984

6.8

1967

7.3

1994

6.7

2006

6.3