1970

5.6

2003

7.2

1999

6.6

2007

7.2

2006

6.7

1998

7.4

1992

6.6

1983

7.4

1995

7.3

2002

6.6

2016

6.1

1988

5.0

1997

6.3

1984

6.8

1981

6.4

1994

6.7

2011

5.9

2005

7.2

1964

6.8

2005

6.2