1994

5.7

2003

7.2

2006

6.6

2003

8.3

2004

6.3

1997

6.5

1992

7.4

1990

6.7

1999

7.1

2007

5.3

1994

7.4

1991

7.1

1980

4.8

1975

5.8

2000

5.0

1992

6.0

2004

4.7

2008

5.3

1995

6.3

2013

5.9