1970

5.6

2003

7.2

1999

6.6

2007

7.2

1998

7.4

1992

6.6

1991

6.1

1983

7.4

1993

7.5

1991

6.6

2002

6.6

1997

6.2

1965

6.1

2016

6.1

1988

5.0

1997

6.3

1998

6.6

1984

6.8

1994

6.7

1996

6.4