1999

5.6

1998

5.7

1997

7.6

2005

6.8

1975

5.8

2006

5.0

1996

6.1

1971

6.6

2003

5.4

2008

5.4

2017

6.3

1992

5.4

2008

7.0

2007

5.5

1994

6.7

2004

6.5

2001

6.1

1985

7.5

1992

5.8

2008

6.2