Non-linearity of wattage to SPL...

I know as wattage increases SPL increase isn't linear, but my questions is if at 1 watt there's an SPL of say 90dB, what wattage would it takke to reach 93dB?

Also, a speaker with a sensitivity of 102dB at 1 watt, what SPL would it put out at 10w, 100w and 500w?

I just don't know what the curve for the increase in SPL looks like, and it's been bothering me that I don't know...
db's are simply the log of a ratio,

so a doubling of power is 2/1

and when dealing with power we mutilply by 10 hence

10*log 2 = 3db

so an increase from 2 to 16 watts is :

10*log 16/2 = 9db

When dealing with voltage then you multiply by 20. Also you have to be careful with the sign and context of where it's quoted, because you could be talking 3dbs down (attenuated) or 3 db up (gain) or even -3db down (gain!).

If i had a filter and at a particular frequancy, on the input i had 10 volts and on the output there was 5 volts, i could calculate how many db's the signal is being attenuated :
20 *log 10/5 = 6db