Storage. Best humidity at time of vacuum sealing? Flower

I need to store dried flower for about 6-12 months.

I'll be using 4mm bags, likely mylar, stored in a temp controlled area about 68 F.

I know humidity at the time of vacuum storage is one of the most important factors.

Does anyone have advice on humidity % to prevent - or lessen - degradation? I mean at the time of sealing, not in the long term storage area. Thanks.