This is related to How can I increase my Vault Dweller's Happiness?, but slightly different.
I know what can raise a dweller's happiness, but what I want to know is what can raise it by how much?
For example, being a healthy, unaffected dweller with no job keeps a dweller's happiness at 50%. Then on the other hand, breeding raises it up to 100%. However I have noticed that there are fairly definitive "levels" throughout the vault. Generally at 100%, 90-80%, 75%, and 50%.
I know what can lower a dweller's happiness, and I know that breeding is a guaranteed boost to 100%, but I can't always afford to have a Vault full of pregnant women.
So, to clarify my question - What Vault features raise a dweller's happiness; and to what level?