While being a damning statistic in itself, I think it is arguably worse when you consider the bigger picture. A high net spend is no indication that a club has spent enough improving their team as it ignores multiple variables, not least age of squad, holes in squad at commencement of the selected time period, long term/career ending injuries etc. I still think gross spend is a better indicator of how a club is likely (or should) be improving year on year. We used to laugh at Liverpool for winning the net spend, because in doing so they won bugger all else. We have been badly managed, but we don't need net spend to tell us that.
I suppose I could google it but I'd be more interested in what our gross spend is in that period (probably the majority of the net spend since we don't sell well)?
If it is the £1,1bn (or let's say £1.3bn) then the sad reality is that is nowhere near enough, given how much we have wasted. That is £110-130m give or take a season shows we haven't spent enough to replace even just the best (few world class) players we lost over the 10yrs to retirement, semi-retirement, free transfers and/or injury. I'd imagine most immediate rival clubs have spent more per season improving their teams/squads. We have also spent irresponsibly that is without question.
We don't "need" transfer (or at least didn't) revenue to balance the books due to our commercial strength, we need and needed to spend the money better, and we definitely needed to spend more to replace some glaring holes in the squad. Other than the optics Net spend has always been largely irrelevant to us, now with FFP it is probably a bit more important.