1991

6.6

1995

6.7

2002

7.2

2004

7.2

2006

7.0

2004

4.6

2003

6.0

2005

5.9

1999

6.8

1998

6.6

1993

5.5

1987

7.3

2006

5.9

2001

7.3

1984

6.0

1997

6.8

2005

6.7

2005

6.8

2015

7.5

1996

6.6