1997

7.1

2009

6.1

2003

7.6

1985

6.7

1967

7.6

2011

6.6

2000

7.2

2015

6.4

1993

6.1

1993

3.7

1999

6.7

2005

5.4

2001

6.1

2000

7.3

1987

7.3

1990

6.0

1993

4.9

1998

5.8

2013

5.9

1989

2.5