1994

6.7

2001

6.3

1996

6.5

1986

6.6

2003

6.4

2005

6.6

2006

5.2

2005

6.1

2002

6.7

1980

7.0

1993

6.6

2006

6.5

2015

5.4

2000

4.8

2007

6.5

1980

4.8

1970

6.1

1993

6.2

1990

6.7

1996

5.6