1997

6.1

2009

5.9

2003

6.3

1997

6.2

1984

5.6

2005

6.5

1980

6.6

2000

7.3

2002

6.4

1992

5.0

2000

6.4

2006

5.3

1974

6.1

2015

5.5

2002

6.0

1992

6.3

2002

5.1

1985

6.0

1975

4.8

2014

4.4