1964

6.2

1990

6.1

1983

7.4

2004

7.3

2002

7.0

2003

5.7

1999

6.0

1979

5.8

1997

5.6

2009

6.0

2017

6.0

2017

7.0

1989

8.5

1993

6.5

1995

6.2

1993

4.4

1984

6.1

1997

6.2

2003

6.2

1994

5.2