'Seeking Curios and Secrets..' Percentages

Anyone got percentages for ‘Seeking Curios and Secrets in the Forgotten Quarter’? I’ve gotten several rare successes, notably a Brass Ring, Pulsating Amber, and an Eyeless Skull. I need to know how often you get those.

There’s a pretty awesome community project here that should help figure out odds (I don’t know who started it, but if anyone knows I’ll update and cite). For what those rare successes are I’d recommend the wiki. For a fan based wiki it’s a remarkably well updated.
edited by MrBurnside on 5/11/2016

There’s a google doc spreadsheet full of calculations, including rare successes such as those.

Beaten to hitting the post button by a good five minutes! Grumble grumble user-unfriendly mobile interface.
edited by Optimatum on 5/11/2016

here’s some calculations of fallingkitten’s: http://i.imgur.com/2wyqTe1.png