1988

5.9

2008

5.7

2007

5.8

2019

6.3

1995

7.2

2000

5.0

1977

5.0

1982

4.1

2013

6.5

1981

6.4

1993

7.0

2006

5.5

2007

6.9

1972

3.1

1974

3.8

2005

6.4

1981

3.8

1979

5.3

1999

3.7

2000

2.6