| Hydref / Autumn | Gwanwyn / Spring | Haf / Summer | Blwyddyn / Year | |
|---|---|---|---|---|
| 2015 / 2016 | 97.7% | 96.4% | 96.9% | 97.04% |
| 2014 / 2015 | 97.42% | 97.43% | 97.75% | 97.52% |
| 2013 / 2014 | 97.64% | 96.78% | 97.21% | 97.05% |
| 2012 / 2013 | 95.83% | 97.34% | 96.56% | 96.5% |
| 2011 / 2012 | 96.7% | 95.9% | 96.57% | 96.4% |
| 2010 / 2011 | 96.27% | 96.0% | 95.9% | 95.9% |
| 2009 / 2010 | 95.9% | 96.0% | 95.9% | 95.9% |
| 2008 / 2009 | 95.5% | 95.6% | 95.7% | 95.4% |
| 2007 / 2008 | 95.9% | 95.9% | 95.4% | 95.8% |
