MQ3 sensor

I use for my project an MQ3 sensor to evaluate the alcohol concentration. I connet the MQ3 to the analog pin of my arduino UNO.
The code that i used is just to give the response of the sensor, but The sensor response is not linear with the voltage.
How i can transfor the response of the sensor to linear response using the analogic pin

if you have a non-linear curve you can approximate it by using multi-map - Arduino Playground - MultiMap -

thanks for reply

the sensor have for the same concentartion different response e.g 36.42 after restart response became 200.36.
I want to know if the analog in pin is for something.