Maybe @ChrisGammell can setup anonym survey in this forum what visitors allows to click on choice for other EDA systems they have or had in use. As Altium enthusiats never visit the Kicad forum this does not give any numbers about market coverage but shows the approximate numbers of users who changed to Kicad or consider to do so while they use old EDA in parallel for compability reasons. For shure, there are many new “one time” users who never did pcb before and would not buy commercial licence but are now allowed to use EDA instead breadboards. Interesting would be the number of designs/year and reasons for change like OS incompability, expired licences or compatible/incompatible migration paths for designs and library. E.g. I know many users from Mentors Expedition who changed to Altium (including sales representatives !) and do not continue their Mentor license becouse of incompabilities from Expedition to Xpedition versions. Together of what we read in other and more general electronics and DIY forums e.g. about the changed Eagle licence policies gives minimum some numbers of growth directions.
To compare: What was the number of sold KiCon Tickets ?