1991

7.5

1982

7.0

1994

8.3

2014

6.0

2009

5.9

1986

7.7

2008

6.2

2004

6.8

2008

6.9

2006

6.5

2000

8.1

1993

5.5

1975

7.1

2008

5.9

2002

5.9

2001

4.4

1999

7.0

2007

7.3

1968

6.9

2008

6.9