Well the survey would include Contiki if engineers chose to mention it.
This survey indicates that less than 2 percent +/- about 2 percent of engineers are using Contiki.
But as you indicate, engineer usage is not the same as installation base.
OOPS, sorry, I switched colors so your comment is right. I wonder however if those figures (all, no only for uC/OS) refer to effective use or are only "intend to use sometime in the future". I remember a few years ago this issue was raised for this or another similar research.
As we unveil EE Times’ 2015 Silicon 60 list, journalist & Silicon 60 researcher Peter Clarke hosts a conversation on startups in the electronics industry. Panelists Dan Armbrust (investment firm Silicon Catalyst), Andrew Kau (venture capital firm Walden International), and Stan Boland (successful serial entrepreneur, former CEO of Neul, Icera) join in the live debate.