Post-BB: All the passive HP boosts

How do these passive HP boosting skills work?

Say you have 5000 HP and add 1 point into the skill giving you a 1% increase, so then you have 5050 HP...when you add the second point for a 2% increase does that mean it adds 101 HP(2% of 5050) to the 5050 for 5151 (and so on as the skill increases)or does it just make your HP 5100 and 5500 at Max?

These kinds of skills never worked that way to begin with. The 20% HP skills give 1.2x HP, same for thief darkness skills except it's 1.1x. o.o