1954

7.9

1997

6.7

1991

6.1

1993

6.2

2002

5.7

1997

6.9

2002

5.4

2001

5.9

2002

6.7

1996

5.6

1998

7.1

1996

7.2

2002

6.6

2001

6.8

2000

7.1

1988

6.3

2006

5.4

2007

5.3

1998

7.0

1971

7.1