Percentage rate of room revenue for utilities

Hi,

Just been trying to fine tune my first year projected budget sheet and I've been trying to decide on what a good guideline percentage to set my utilities expenses to. I've been seeing everything from 10-30% here and there.

It's going to be a 20 bed hostel in Croatia. Smaller size city (not Zagreb). Obviously if anyone on here is from Croatia and has good solid info on the subject that would be great, but any input or advice from anyone who has been in a similar predicament is always appreciated.

I would like to imagine it will be no bigger than 20%, ideally for me 16-17%. That would be an approximate average weekly cost of €100. That would include- electricity, heat (solid wood furnace), water, garbage. Water can be heated by electricity or by the wood furnace.

thank you again!