I don't think it actually tells you anything very useful :-(
Adobe has always been targeted at amateur and professional photographers, while Capture One has only (until recently) been targeted at professionals, has always been priced way higher than Lightroom and initially only supported pro level Nikon and Canon cameras, as a "favour" to professionals using Phase One cameras who also wanted to use Capture One to process their Nikon and Canon files (or it may have been linked to tethering)
I suspect this statement will only apply to proportions and not to actual numbers. ie of the people who use C1, the majority are professionals, while of the people who use Lightroom the majority are amateurs. But that could still be a million professional photographers using Lightroom while only 100,000 professionals using Capture One (I have no idea what the actual numbers might be, this is purely illustrative).
Capture One is still a high priced niche product mainly aimed at professionals and serious amateurs, while Lightroom is aimed at "everyone" who might have a use for a photo processing program, so it would be "very" surprising if more amateur photographer were not using Lightroom than C1, many amateurs will have never even heard of Capture One, even though its been around for longer than Lightroom.
I think what might be more telling, as I suspect very few professional C1 users don't also use Photoshop, is how many pay the extra for C1, even though they have Lightroom for free with Photoshop.