1974

0.0

1990

7.0

2005

7.8

2014

6.9

1980

6.4

2010

5.3

2006

6.7

1981

5.9

2010

7.0

2009

7.3

7.8

2011

6.6

1999

5.9

2011

5.5

1989

7.1

1975

6.0

1989

7.6

1984

6.2

1984

5.6

2017

6.9