1981

7.4

2004

8.0

2003

7.1

2009

6.3

2005

6.6

2003

6.7

1999

7.6

2015

6.4

2011

6.8

1994

6.5

2012

7.4

1989

6.0

1985

6.2

2002

5.7

1986

7.7

2006

6.2

1991

6.8

2002

7.7

1987

7.2

2009

7.5