1987

4.0

1985

5.1

2007

5.4

2006

6.6

1995

7.3

2002

6.6

1981

7.2

2006

6.0

2012

4.0

2015

6.0

2007

6.4

1987

4.1

1973

6.0

1994

5.0

1962

4.7

1973

8.2

2003

8.0

2005

6.5

2000

8.2

1994

8.3