Monitoring multixact members growth

Hello everyone,

Is there a way to monitor multixact members growth per table ?

There is this query:

SELECT relname, relminmxid, mxid_age(relminmxid) AS age
FROM pg_class
WHERE relkind = 'r'
AND relnamespace::regnamespace::text = 'public'
ORDER BY 3 DESC

However it is not quite clear to me how I can interpret results from above and e.g. conclude: my_table accumulates x more multixact members since I measured last.

My goal here is to predict where multixact members are growing the fastest so I can perform manual VACUUM FREEZE only on those tables
(typically with multi-billion row count) when system is relatively idle as opposed to just sit and wait for wraparound protection to take over
when autovacuum_multixact_freeze_max_age threshold is reached (slowing the whole system down).

Please advise on how to achieve this.

Best regards,
Vido