1992

6.7

2002

6.3

1990

6.1

2008

8.5

1999

6.6

1961

7.2

1990

7.8

2010

6.5

1951

7.2

1985

7.7

1952

6.7

2009

7.5

2003

6.7

2004

7.3

1988

6.2

1966

7.8

2005

6.7

2003

6.1

1981

7.0

2016

5.7