Follow the format for a website reference. There is no print equivalent of Hit Songs Deconstructed so this is probably the closest match.
AUTHOR, Year. Title of chart/report [with any search limits placed] [viewed date]. Available from: URL
HIT SONGS DECONSTRUCTED, 2017. Lead vocal gender [Q1 2016 - Q4 2016] [viewed 21 February 2017]. Available from: http://db.hitsongsdeconstructed.com
If you end up with lots of references to charts or reports for the same year within one assignment, you need to reference them as ... (Hit Songs Deconstructed 2017a) ... (Hit Songs Deconstructed 2017b) and so on (with these letters added to the appropriate full entry too).