1997

6.8

1995

5.8

2007

6.8

1993

6.5

1992

6.8

1991

6.7

2004

6.2

1990

5.7

1987

6.8

1964

6.2

2007

6.5

2003

7.2

1989

6.0

1993

6.7

1986

7.0

1991

6.1

1986

6.1

1997

6.6

1992

6.7

2004

6.4