1990

6.4

1994

5.2

2006

6.7

2008

6.4

2007

7.1

2002

6.3

2002

5.9

1985

7.1

1996

7.5

1972

6.2

2007

7.9

1993

6.2

2014

6.1

1997

6.5

1986

6.6

2005

6.6

2006

6.9

2004

7.2

2000

6.0

1993

6.2