Mixing HGH for 2IU shots

I hate to sound stupid. But I am having trouble figuring out how much Bac Water to put in a 15iu HGH Bottle. I want to have 2iu injections with a 1ML Insulin Syringe.

Advise appreciated.

Here you go

You can either add 15ml to the vial so that 1 mL equals 1iu or you can add 7.5 mL to the vial and 1 mL would equal 2iu.