1990

6.1

1988

6.1

1996

5.8

1993

5.8

1989

5.5

1999

5.1

1987

5.3

1976

7.5

2004

5.7

1994

5.3

2002

7.5

2009

4.8

1991

5.6

2003

6.8

1997

6.4

2006

6.8

2013

6.7

1996

5.2

2012

6.9

2011

6.3