2006

4.7615

2007

4.9071

2008

5.2982

2009

5.5896

2010

5.6606

2011

5.5631

2012

5.5155

2013

5.5961

2014

5.4963

2015

5.5895

2016

5.7992

2017

6.0201

2018

5.9871

2019

6.1098

2020

6.2399

2021

6.3500