1974

5.8

1991

5.1

2000

4.4

1993

6.2

2002

6.1

1984

4.8

1998

5.0

1988

7.3

1981

6.8

1987

6.8

2009

6.7

2005

6.8

1989

5.8

2002

5.5

2008

4.8

2006

3.9

2003

5.8

1990

4.7

2017

5.7

2004

7.1