1985

5.8

1997

6.2

1999

5.1

1986

5.6

2003

6.6

2002

5.8

1968

6.4

1988

6.1

1996

8.1

2011

5.5

2012

6.3

1996

5.8

2004

5.7

2009

7.2

2006

7.8

1990

6.1

1942

7.3

1995

4.7

2012

6.1

1988

5.8