Some numbers here : http://www.aerovfr.com/2020/12/quelques-chiffres-sur-les-carburants-aviation/
Avgas sales in France alone are about 23000 cubic meters, ie 16000 tons. The world uses about 1 million tons.
JetA usage is considerably higher, about 400 times in France.
This was posted on a US site which I think is behind a registration. FWIW:
It is of course interesting, but I would be a bit careful taking everything at face value, because in recent years I have seen a number of similar posts made on forums by people who claimed to have worked in the business, and most of them spread the same message of doom and gloom. This one may well be credible though.
Swift fuel organized a flight with an RV-8 fueled by a prototype 100LL-replacement, 97% plant-based.
Press release announcing the flight (in english)
Article about the flight (in french)
Looks like Avgas has finally a replacement showing up, called 100R, lead-free and acceptable for all avgas engines. 
Note :
Europe burns 100M liters of avgas a year.
US 900M liters, depsite LOP
Gives you an idea of the difference in GA traffic
The economies of the EU 27 and the USA are essentially the same, and Europe has slightly larger landmass.
But we burn 90% less Avgas Tells you everything you need to know about ho challenging it is to fly here.
Or put another way, how easy and accepted it is in the US.
I think there is no doubt that the USA flies more hours on piston engine aircraft using Avgas than Europe.
However, I think one must be a little careful by just comparing Avgas usage in Europe and USA to make any point other than that.
One also has to ask how much diesel/Jet fuel is used, in each country. Are diesel engines more popular and used more for ga aircraft in Europe.
And how does the ULM sector compare? Is there a large ULM market in the USA and is it using mogas? Is there a great deal of difference pricewise between the fuels that would make aircraft owners choose a particular type of engine?
From posts in this forum it would seem much more challenging to get Avgas in some European Countries. Some of these countries make ga flying more challenging in general.
IMO Avgas has to be both more available throughout Europe and prices need to be nearer the lowest available if it is to survive in Europe into the future. The question is whether that is likely.
Having lifted avgas in Arcadia, Florida at 3$/Gal and in Almeria, Spain at 15$/Gal, I would say +900% more can’t be explained by -80% price discount alone !
No question it’s still a huge difference, which alone is sufficient to explain differences in usage of AVGAS. But “MOGAS” and Diesel seems to be used a lot more here than there.
Lots of places in the US with 7$/gal Avgas, and many places in Europe with 8$/gal…
I would never have guessed that Europe uses that much Avgas. It must be in specific locations because the overall impression is of very little GA operations.
My US base has about 450 based aircraft and 625 operations per day per FAA data. Also a ‘hotspot’ in terms of US activity which probably drives my perception when comparing to European areas which are not the local hotspots. 100LL fuel today is $4.65/gallon.
“97% plant-based”
Many of us consider it morally repugnant to kill people who have avgas if we cannot get any.
We may have different views for getting food after a day or so without it.
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