1979

8.3

2002

7.6

2004

7.8

1993

7.7

1987

5.0

1999

6.5

1975

7.3

2000

6.1

2006

5.3

2005

6.2

1993

6.6

1990

5.6

1999

6.0

1985

6.7

1997

6.2

1994

6.2

2015

6.3

2013

6.2

2009

6.9

1963

6.9