This is what happens after another 4 loads are hauled:
And this is what happens a month later (no more troops hauled):

Edit: I think I know what's happening - it's counting YTD every week, so it will add on 5 to 5 to 5 to 5 etc every week?? Is that it?

I don't think there's an answer to this one, I think it's going to have to be a year-end count unless anybody else can think of anything? Thanks for all your help, anyway!
