When I have a perk that has multiple ranks, do the given bonuses stack, or are they cumulative?

For example, the archery skill Overdraw has 5 ranks.
The first rank gives +20% damage.
The second rank gives +40% damage.

Upon choosing the second rank, do I now deal out +60% damage, or does each rank only increase the damage by +20%?

I believe it is just the +20% each time you upgrade a weapon skill. So through perks you will only ever raise your damage to +100%. Which is still a danm good return.

Ok, that is what I assumed, but I wasn't positive.

I figured if it was stacking each time, I'd be able to spread the points out a little more...
but since the bonus shown is cumulative, it makes more sense to max it out.