chickens incubating & still air humidity %

[snaphu]

this is my first time incubating

....

I have 20 eggs in a Hova-Bator Still-Air Incubator model 1602N, what is the humidity that I need for success?

thanks
Sue

 

[SundownWaterfowl]

Day 1-18 around 35-40%, day 18-20 (hatch time) around 65-70%, since its a still air. I keep it a little higher around 75% for my forced air.