2006

3.5

1997

3.2

2003

5.7

1974

3.8

1971

6.0

1990

3.5

1993

5.6

2014

5.3

1977

3.4

1980

4.3

2015

6.3

1989

4.8

1978

4.2

1989

3.7

1992

4.7

2000

5.2

1982

6.0

1973

5.4

1994

4.4

1975

5.8