Dated 10 Nov 2014
"In total, it takes Flybe’s routes to 17 to and from Manchester, with up to 660 flights a week." So accordingly to that article that's 330 weekly departures.
Flybe start new daily service from Manchester Airport to Amsterdam - Manchester Evening News
But two days after this Bournemouth was added at 12 weekly, so possibly 342 departures ?
Sure there are more than 18 destinations though aswell ??