1986

6.8

2000

5.5

1984

7.3

1971

6.4

1998

6.0

2002

5.2

1994

6.6

2010

5.7

1951

6.4

1968

6.9

1990

6.1

2009

5.0

1995

6.5

2001

6.4

1990

6.5

1983

6.5

2004

6.7

2005

6.3

1999

7.6

1993

6.2