+1 skill gem on bow

Anyone know what the odds are for getting +1 skill gems on a bow. I am currently scouring and then hitting my bow with the deafening essence of dread.

the idea is that I get +2 bow skills and +1 skill gems

anyone here know the odds of getting that +1 skill gem roll?

According to Poe.DB, it says 0.42%. I am assuming it is including the elder, shaper, and delve mods, so perhaps it is higher than that if your weapon cannot roll those.

If someone could clarify the percentages when you click on a mod on poe.db that would be great.