1968

7.6

2006

6.2

1990

6.5

1999

6.5

2007

7.2

1987

6.9

1975

5.5

1988

7.1

2008

6.7

1976

5.6

1995

4.1

1969

3.8

1993

7.8

2002

5.6

2014

5.2

2017

6.4

2009

7.5

2005

6.3

2017

1.0

1992

5.9