1988

5.0

1999

7.4

2003

5.9

2013

6.7

2013

4.3

2012

6.1

2012

5.8

1996

6.6

2002

7.1

2005

6.3

2009

4.5

1999

6.8

1998

6.6

2002

7.2

1995

3.3

1995

6.7

1993

5.5

1972

2.4

1990

5.7

1990

4.2