1997

6.8

2005

6.7

2017

4.9

1976

3.3

2014

5.8

1991

3.8

2007

5.9

1986

6.3

1979

6.3

1981

6.0

1982

6.0

1987

5.6

1994

5.8

2003

6.1

2004

6.7

2002

5.3

2002

4.8

1974

5.9

1974

1.5

1972

1.0