Page 38 states that 62.2% of staff were female.

Therefore 31312 x (62.2/100) = 19476.064.

Add to that temporary female staff: 448 (African) + 81 (Coloured) + 90 (Indian) + 151 (White) + 27 (Foreign) = 797

19476 + 797 = 20273

On page 30 in the 2015 Sustainability Review report, it gives the breakdown of temporary employees as mentioned above