1978

6.8

1997

6.7

1992

6.6

1984

7.4

1987

7.9

1986

4.0

2003

7.4

1981

6.7

2002

7.4

2015

6.9

1992

5.3

1981

6.6

1988

5.5

1999

6.4

1991

7.8

2009

8.5

2014

2.0

2005

5.0

1997

3.5

2012

7.0