| Date | Percentage |
|---|---|
| 2nd November 2017 | 0.50% |
| 4th August 2016 | 0.25% |
| 5th March 2009 | 0.50% |
| 5th February 2009 | 1.00% |
| 8th January 2009 | 1.50% |
| 4th December 2008 | 2.00% |
| 6th November 2008 | 3.0% |
| 8th October 2008 | 4.50% |
| 10th April 2008 | 5.00% |
| 7th February 2008 | 5.25% |
| 6th December 2007 | 5.50% |
| 5th July 2007 | 5.75% |
| 10th May 2007 | 5.50% |
| 11th January 2007 | 5.25% |
| 9th November 2006 | 5.00% |
| 3rd August 2006 | 4.75% |
| 4th August 2005 | 4.50% |