The discovery of a large fab-to-fab variability in the TID response of the CMOS technologies used in the design of ASICs for the particle detectors of the HL-LHC triggered a monitoring effort to verify the consistency of the CMOS production process over time. As of 2014, 22 chips from 3 different fabs in 130 nm CMOS technology and 11 chips from 2 different fabs in 65 nm CMOS technology have been irradiated to ultra-high doses, ranging from 100 Mrad(SiO2) to 1 Grad(SiO2). This unprecedented monitoring effort revealed significant fab-to-fab and run-to-run variability, both dependent on the characteristics of the MOS transistors.