| Year | ||||||||||||
| 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | Total | |
| Staff | 9 | 6 | 8 | 5 | 3 | 9 | 5 | 1 | 2 | 8 | 7 | 63 |
| Percentage | 14.3% | 9.6% | 12.7% | 7.9% | 4.8% | 14.2% | 7.9% | 1.6% | 3.2% | 12.7% | 11.1% | 100% |