The point I was making in my message was that ICANN funds all of the IANA naming functions but does not fund all of the IETF and RIR costs related to IANA processes.
How do you know that? I thought this was a free service for the IETF.

No entity is charged for IANA services. Really.

I admit I don't know the numbers contribution levels for the IANA service, but I am pretty sure IETF pays nothing for it.

There are no "contribution levels for IANA services." The IETF does not provide any funding to ICANN. Nor do the .INT registrants. The RIRs and some ccTLDs provide a voluntary contribution to ICANN, but that accounts for a tiny fraction of ICANN's revenues.

Regards,

-drc