Does Unrest optimally go down on its own?

[rabelais]

Hiya.

Search didn't turn up an answer so I'm posting a terribly newbie question.

Will unrest never decrease without either tax reduction or patroling?

e.g. if I have a province with 8 unrest, will having a highly ordered friendly dominion eventually get rid of it, or is it permanent without an event, or one of the behaviors above?

Also which random events have nonzero unrest requirements and what are the thresholds?

Thanks,

Rabe