1994

7.1

2012

6.6

2016

6.7

2020

6.0

2000

6.8

2013

6.1

1988

8.4

1961

7.4

1989

6.4

2007

7.5

2006

7.0

2002

7.6

1997

6.5

2005

6.8

2014

8.5

1971

6.9

1999

6.7

1983

6.5

1989

7.1

2010

6.0