| Date | Assets and liabilities | 
| 2005 | 0.675783 | 
| 2006 | 0.713404 | 
| 2007 | 0.687515 | 
| 2008 | 0.729145 | 
| 2009 | 0.728727 | 
| 2010 | 0.752093 | 
| 2011 | 0.796061 | 
| 2012 | 0.820908 | 
| 2013 | 0.839991 | 
| 2014 | 0.845494 | 
| 2015 | 0.869648 |