1997

6.8

2003

7.1

2007

6.7

1993

6.5

2003

6.1

2007

7.3

1997

6.4

2004

6.9

2015

5.4

1998

6.3

2003

6.2

1988

6.3

1994

5.8

1990

6.7

2002

6.7

1993

6.6

1973

8.0

1992

6.7

2004

6.4

2006

7.0