Came here to essentially say the same thing you mentioned in your second sentence.  In terms of how many Ubuntu containers have been launched, it could easily be in the billions.  Docker makes OSes so ephemeral that any statistic on launched Ubuntu instances is meaningless.<p>The down side of containerization for Canonical though, is that as engineers get more sophisticated with microservices and Docker in general, container images are built from much smaller distros such as Alpine, Busybox and even from Scratch.<p>(disclosure: I work for Docker)