Worldwide participation of fewer than 100

Since all of the more than 50 "magistrates", "senators" and "priests" are required to pay this "tax"or lose their positions, the numbers show that very few indeed who are not in those groups (the power holders) bother to pay.

Update:

This was just announced.

Edictum censoris Iuli Sabini de capite censi anno MMDCCLXIV.
1. Due to the not payment of the annual tax, the following Nova Roma's Senators and magistrates:

• Marcus Iulius Perusianus – Senator,

• Emilia Curia Finnica – Senatrix,

• Marcus Curiatius Complutensis – Senator,

• Gaius Flavius Diocletianus – Senator,

• Appia Domitia Taura – Quaestor,

are considered capite censi, suspended from their function, placed in the last century and urban tribes, without the right to attend or observe the Senate sessions, run for offices or be appointed as apparitores or provincial governors.
The suspension is valid until a censor suffectus is elected, when their final situation will be decided in concordance with the laws of Nova Roma.
2. Other categories of capite censi officials are subject of analysis and decisions of the Nova Roman institutions which elected, nominated or appointed them.

This means that with resignations and expulsions, 14 of roughly 33 "magistrates" positions are now vacant. Point #2 above, "Other categories of capite censi officials are subject of analysis and decisions of the Nova Roman institutions which elected, nominated or appointed them", means that more vacancies are likely to come.