1997

7.0

2004

7.5

1999

6.8

2015

5.4

1995

6.9

2005

6.2

2007

6.6

1991

6.7

2006

4.4

2002

6.1

2003

7.1

1980

6.8

2000

7.1

2007

6.7

1997

7.6

2001

5.7

2000

5.0

2003

6.1

1994

6.2

1979

8.3