So how does that really work? You would logically think that an annexed country would give more than an occupied, no? So, how much less to you get from an annexed country, roughly?
Umm, let's see, the 'non core' penalty that annexed areas get is
non_core = {
local_manpower_modifier = -0.75
local_leadership_modifier = -0.80
local_ic = -0.50
local_resources = -0.5
Closest to this is the occupation law of full occupation.
local_manpower_modifier = -0.75
local_leadership_modifier = -0.80
local_ic = -0.50
local_resources = -0.2
Immediately, it's bonus of 30% resources.
However, since it's bit hard to make out the difference between the other things than resources (as you can't get mouseover view out of them) I'll dabble this with 'collaboration goverment' example, that has the same -50% to resources as annexation (and is most used anyways for manpower gains and low revolt risk).
So, let's see, I found two provinces with 15 energy, annexed one gets non core -50%, revolt risk -11,4%, +5% from tech for end result of 6,1 energy per day. Occupied one, -50% from occupation policy 0% from revolt risk (aye, there's a garrison of infantry here, enough to drop it that low over time...) +5% from tech, 7,9 energy per day...
So 6,1 vs 7,9 (the annexed revolt risk can't be dropped), so 29% more resources gained due to the lack of revolt risk, and I'm pretty sure revolt risk reduces IC, manpower (and leadership?) as well, so essentially you could write the annexation numbers as (with the initial 6% lowest possible revolt risk);
local_manpower_modifier = -0.87
local_leadership_modifier = -0.92
local_ic = -0.62
local_resources = -0.62
Which is really crappy, sure, occupation policies give some revolt risk, and most of the time I don't get around to supressing it, but with the usual collaboration goverment it's still only 1%...
...and you get to change them depending on your IC need against the others...
Wish I had a large scale example, but I don't know if I have any 'pre annexation save' that would have chance of exile or annexation.