1980

7.2

2010

7.1

1998

6.6

1988

6.1

2013

7.6

1990

5.5

2010

6.0

2006

6.5

2014

6.1

1998

7.5

1989

6.2

2015

5.9

2009

5.5

2014

5.8

1999

8.0

2007

7.6

1951

7.6

2011

7.1

2010

6.1

1987

5.5