Where is the information to come from that gives a reasonably accurate picture of what the trend is in terms of film sales and if this exists then we can start to extrapolate future sales figures etc?
Harman Technology Limited (Ilford etc) has to publish accounts each year and you can see them for free at this address
https://find-and-update.company-information.service.gov.uk/company/05227615/filing-history. They put comments about the industry in there. For the 12 months ended 31 December 2019 they said this:
"Film sales continued to grow well with volume growth of 5%, reflecting the continued resurgence in analogue photography interest, particularly among those under 35 yrs old. By contrast paper volume declined 8% in volume when compared to 2018. This reflects the artificially strong paper sales in 2019 (as the US supply chain continued to refill following the former distributers demise into administration), whilst also incorporating the overall longer term trend of lower volumes that is being seen across all print platforms.
Supporting products for the film and paper continue to do well, reflecting the higher overall interest in analogue photography with revenue for the processing chemicals and darkroom accessories both growing by 10%"
So film volume grew 5%, and paper volume fell. And they quoted revenues for the third point, so you would have to work out what the price increase % was for chemicals and darkroom accessories to tell if 10% revenue growth equated to a volume growth or not. The fact that volume was not quoted on that one is interesting as volume was quoted else where.
2019 turnover for Harman was £23m GBP / c$32m USD ( I would guess smaller than many on here would imagine). Take some assumptions about the split of film/paper/chemicals/accessories, then and assumption for list price to wholesale ratio and you can haves some fun guestimating the unit volumes of each sold...but I can save you some time, volume is low in the grand scheme of things for worldwide demand. You can also do the same over time as historical accounts are at that URL for free too.
Revenue split is 12% for UK, 26% for EU, and the rest is stated as just ROW.
Their accounts for the year ended 31 December 2020 are due to be submitted by the end of this month so we can see the C19 impact, will be interesting reading.