The EU Commission published a [handbook detailing how the system works](https://ec.europa.eu/clima/sites/clima/files/docs/ets_handbook_en.pdf). I cannot say that I am confident that I fully understand it but the process is quite a bit more involved than simply a top-down allocation of a total number of certificates.

Instead, a number of certificates is computed for each “installation” (industrial site) based on historical activity levels and a technology benchmark. Then these numbers are aggregated, some certificates are set aside for new entrants, member states with low income, and member states that already reduced emissions by 2005 and a reduction coefficient is applied each year. Each member state gets to allocate the certificates that are left through two different mechanisms (free allocation and auction). On top of that, there is an entirely separate system for the aviation sector.

The rules for computation are defined by EU law and the EU Commission has a role throughout the process but the member states are in charge of measurement and computation. *They* submit a document that the Commission merely reviews. [The list for Germany is available here](https://www.dehst.de/EN/european-emissions-trading/installation-operators/2021-2030/allocation-2021-2030/allocation_2021-2030_node.html).

Importantly, certificates that get auctioned can be bought by businesses anywhere in the countries participating in the system (and not only by those based in the member states organising the auction). Since the relevant member states gets to keep the revenue, it still makes sense to ask how many certificates they were issued in the first place.