What was the (a) address, (b) value, (c) size, (d) reason for not being utilised, (e) amount of rates and taxes paid on and (f) amount spent on the maintenance of each under-utilised and unutilised property owned by his department (i) in the (aa) 2015-16, (bb) 2016-17 and (cc) 2017-18 financial years and (iii) since 1 April 2018