How many (a) Senior Management Services posts existed and (b) officials were employed in each (aa) national and (bb) provincial (aaa) department and (bbb) each entity or unit reporting to the respective departments, in the (i) 2011-12, (ii) 2012-13, (iii) 2013-14, (iv) 2014-15 and (v) 2015-16 financial years?