(1) With reference to child trafficking, what is the estimated number of minor children who have entered the country but have not been recorded as leaving the country in (a) 2012, (b) 2013 and (c) 2014 and from 1 January 2015 up to the latest specified date for which information is available; (2) what is the source of the data provided; (3) has his department ever conducted any studies into the rates of child trafficking in or out of the country?