1986

7.0

2002

6.2

1999

5.2

1981

6.6

1984

5.0

2006

7.2

2003

6.0

2003

5.1

1987

6.8

1975

7.2

1981

6.5

2005

6.3

1988

5.0

1973

7.4

2001

6.8

2002

6.7

1996

5.6

2003

6.2

2008

5.4

2004

5.3