1981

6.6

1987

5.2

2009

7.0

2011

7.4

1995

7.2

1992

7.0

2011

7.5

1986

7.3

1997

7.5

1993

6.1

2003

7.4

2013

0.0

2018

4.7

1984

6.7

1999

4.8