1971

6.4

2008

6.6

2007

6.1

1997

6.8

2004

7.6

2006

7.0

2000

6.0

2014

4.0

2001

6.1

1968

6.5

1988

5.3

2007

6.0

1993

6.1

2007

5.2

2013

3.6

1986

6.1

2005

4.9

2000

7.3

1981

0.0

1999

7.0