How does the AI decide on Cardinal allocation?

[RMS Oceanic]

So I have several high dev catholic provinces, and good relations (though not alliance) with the Pope. This little indicator says how likely it is for one of my cities to get a Cardinal, but even when I devpushed Berlin to over 30 and it said a 20% chance, I'm sitting with nothing while Northern Italy is stuffed full of Cardinals. Is there a weighted bias in allocation, and what's the best way to manipulate it? How are these percentages I'm seeing determined, and when are the decision taken outside of events?

 

[The_Boominator]

This is why Germany goes Protestant.

In all seriousness, it's just a matter of RNG. It's generally a good idea to improve relations with the Pope early to improve your chances as not all cardinal slots are filled and they will be assigned gradually. The best thing you can do is improve relations with the pope, keep the clergy happy, and dev a few provinces. Emphasis on a "few" for the reasons mentioned here. I notice the emperor also tends to get a lot of cardinals, perhaps because of how the title interacts with tax income. Almost every time I become emperor I get 5-7 cardinals.

 

[EarlKonrad]

Just to add to what the poster before me said, the only Dev type that matters for cardinals is Tax so high Tax provinces are more likely to get cardinals.