IPC: core vs advanced level in patstat

As very vell explained from EPO website (here) IPC classification contains over 70.000 entries, that give too much detail for most users.
That's the reason why aside from this advanced classification has been introduced a core classification containing "only" 20.000 entries.
The advanced level is a superset of the core level, ie it consists of all core level groups and many finer subdivisions, allows updates to be made every three months, which means it will grow considerably in the years ahead.
In PCT minimum documentation have an advanced-level IPC. They also have a core level IPC that is derived from the advanced level.

In patstat we can distinguish advanced and core levels by the content (A or C) of field IPC_CLASS_LEVEL in table tls209_appln_ipc.

I ran a query in order to understand how A & C IPCs are distributed across the various patent offices (see the SQL below) expecting a 1:1 distribution.

SELECT tls201_appln.APPLN_AUTH, tls209_appln_ipc.IPC_CLASS_LEVEL,  COUNT(tls209_appln_ipc.APPLN_ID)
FROM patstat.tls209_appln_ipc
INNER JOIN patstat.tls201_appln ON tls209_appln_ipc.APPLN_ID = tls201_appln.APPLN_ID
GROUP BY tls201_appln.APPLN_AUTH, tls209_appln_ipc.IPC_CLASS_LEVEL
ORDER BY tls201_appln.APPLN_AUTH, tls209_appln_ipc.IPC_CLASS_LEVEL;

The full results of the query may be downloaded here; bytheway I publish here a graph of patenting office with more than 850.000 C and A IPCs: in red you may find the count of CORE ipcs, in blu the ADVANCED ones.

At a glance we notice that, apart from Slovenia Patent office (SI), everywhere the figure of advanced IPCs is the higher, average above 10%.
The peak of difference is to be found in some african countries (34% Kenia, 36% Malawi) but also in Iceland advanced ipcs are 31% more than core ones. Same trend in US (11%), EP (15%) and  JP (12%).