What (a) was the total production of rough diamonds in (i) carats and (ii) rand in (aa) 2008 and (bb) 2009, (b) was the volume of trade in rough diamonds by the State Diamond Trader in (i) 2008 and (ii) 2009 and (c) is the reason for the low levels of trade in diamonds by the State Diamond Trader for the period relative to the industry volumes?