Sorry, but nope, I don't understand it that way. Perhaps we need to properly define utilization.
For the purposes of the RIRs and for any ISP assigning or allocating address space downstream, 'utilization' refers to an appropriate assignment made. If I have properly assigned 80% of an address block to my customers, I am 80% 'utilized' for the purposes of the RIRs. It is entirely irrelevant how much address space is actually being used, on an IP x IP basis by downstreams. If the assignments were justified per RFC2050, and the upstream has assigned 80% or more of its available address space, then it requires another block.
To an end user, it means active hosts. ARIN suggests following RFC2050 and the 25%/50% standard prior to receiving an additional address assignment from their ISP.
Please stop saying that. ARIN requires ISPs to follow RFC2050's guidelines for *initial* assignments to end-users. End-users must demonstrate a need for 25% of the requested assignment immediately, and a need for 50% of the requested assignment within one year. For *additional* address assignments from an ISP, an end-user should demonstrate that they have utilized (in this case, meaning active utilization in a 'live' sense) 80% of the initial assignment. The difference is an important one. 25-50 is for *initial*, 80 is for *additional*.
This is even more confusing when the customer is both an end user and a downstream ISP themselves. If they aren't in turn assigning address space, then they are simply an end user and should be following RFC2050.
The RIRs use the words "ISP" and "end-user" slightly differently than other folks. Any organization which does not assign their address space further downstream is considered an "end-user". It doesn't matter what their business activities are (indeed, they may be a service provider). For the purposes of this discussion, for the purposes of the RIRs, they are an end-user. /david