1995

6.0

1995

5.8

2003

5.8

2002

7.3

1999

6.8

2006

6.8

1991

6.1

1990

6.7

1993

5.4

2002

6.3

1981

7.1

1999

7.2

2007

6.1

2000

7.4

1988

6.2

2006

6.3

1974

3.5

2004

6.7

1961

7.4

1986

2.0