How many senior officials have resigned from the National Ports Authority (NPA) (a)(i) during the period 1 January 2007 to 31 December 2009 and (ii) during the period 31 December up to the latest specified date for which information is available, (b) what is the name of each person who has resigned, (c) what post did each such person hold at the time of his/her resignation, (d) what were the reasons for the resignation and (e) what was the nature of the retrenchment package each person received?