1991

6.4

1999

7.0

1992

6.8

2002

5.9

1997

6.1

1986

6.7

1965

6.3

1955

6.6

2008

7.6

1959

6.3

2016

6.3

2008

6.6

2004

6.1

2003

6.3

2006

5.1

1986

6.1

1996

5.2

1979

7.3

1994

6.7

2008

5.7