We only want customers with a minimum 3 year perspective. We also need predictability for our investments in build of datacenters. Since the main investment cost has to be made regardless of 3 or 5 years the yearly price for a 5 year contract is cheaper and the best option if you are looking for a long term perspective. Since our contracts include electricity and maintenance there is no risk we will stop mining in the future because we cannot afford to pay electricity bills.