When you say most, is that just a guess? Do you have a figure in mind or are you just assuming?

I actually decided to look up some more articles on industrial greenhouses. They're all agreeing with me:

https://extension.okstate.edu/fact-sheets/greenhouse-carbon-dioxide-supplementation.html#:~:text=The%20ambient%20CO%202%20(naturally,at%20night%20in%20sealed%20greenhouses.

An increase in ambient CO2 to 800-1000 ppm can increase yield of C3 plants up to 40 to 100 percent and C4 plants by 10 to 25 percent while keeping other inputs at an optimum level. Plants show a positive response up to 700 to need of 1,800 parts per million, but higher levels of CO2 may cause plant damage (Figure 1).

https://www.ontario.ca/page/supplemental-carbon-dioxide-greenhouses

Higher than recommended levels can cause necrosis of old tomato and cucumber leaves. African violet leaves become very hard and brittle, show a very dark greenish-grey colour and often malformed flower petals, which do not fully expand. A similar symptom with freesia flowers has been observed where the CO2 burner was used to provide the majority of the heat requirements of the greenhouse, and thereby generating excessive amounts of CO2. Except in emergencies, do not use CO2 burners as the prime heating system.