Shares on issue on the day of the announcement of the buy back...

Shares on issue on the day of the announcement of the buy back (24/11/15) - 200,500,001

10% of issued capital over 12 months = 20,050,000

12/5/15 - 16,914,550 Per this morning's announcement
13/5/15 - 2,326,271 (Assumes all traded were part of the buyback)
Total = 19,240,821

Still 809,179 shares to be bought on market, although its effectively reached it limit. Who knows though they could extend it given the success it's had.

Since the announcement of the buyback the share price has risen 93% from 3.1c to 6.1c