Probably not info the CI companies all want public. That's within margin of error of their exact customer counts I would think
Why?
Because a lot of organization use privately hosted CI/CD systems, such as concourse. :-)
Someone might use this chart to make decisions for their team, and the usage patterns for open source is likely very different from someone using CI for internal development and deployment. (For instance, Travis CI is very popular, but when I've looked at it in the past, it was pricey relative to options like Codeship and CircleCI for private workloads)