1987

5.3

1990

6.0

1993

6.5

2013

6.5

2012

7.6

2007

5.5

2002

5.6

2010

5.8

2003

6.8

1982

5.4

2014

6.3

2017

6.9

2019

6.5

1985

6.7

1978

5.9

1999

5.6

2009

4.6

2008

5.8

2002

5.8

2015

6.7