1969

5.3

2011

6.1

2009

5.6

2009

7.7

2010

5.6

1988

6.5

1957

7.2

1986

6.8

2005

7.8

1984

7.3

1999

6.3

1991

6.5

2005

5.2

2002

6.4

2004

7.3

1992

6.9

2015

7.1

1993

6.6

2010

7.2

1972

7.2