How much does one credit cost you

I was wondering how much money one credit cost.
I assume it depends on the machine running, the cost of electricity and if you want the wear of your hardware.

For my Host ID 11670866 one credit costs about 0,000017777€ of electricity.

For my Host ID 5938675 it is 0,0000325€ of electricity per credit.

This is calculated with a kwh costing 0.30€

I would be interested in your costs. Who has the most costs? where is electricity cheap? Which machine runs most efficient?