1990

6.2

1991

6.8

1992

6.2

2009

4.6

2006

4.7

1994

6.5

1961

7.7

1971

7.2

1993

6.3

1983

5.9

1958

7.6

1981

7.1

2007

6.2

2008

6.6

2004

7.0

1986

5.8

1999

6.8

1990

6.4

1994

5.8

1997

6.8