1969

3.8

1986

4.5

1989

5.8

1984

6.8

2008

7.3

1997

5.4

1987

4.1

2005

6.5

2005

6.1

1996

6.7

1973

6.4

1987

6.4

2005

5.3

1985

6.6

2014

6.0

2003

6.0

2007

6.6

2010

4.8

2006

4.1

1962

0.0