A​ company's charge for electricity is 9.173​¢ per​ kilowatt-hour. In​ addition, each monthly bill contains a customer charge of ​$6.11. If last​ year's bills ranged from a low of ​$61.59 to a high of ​$241.39​, over what range did usage vary​ (in kilowatt-hours)? The range of use in​ kilowatt-hours varied from __ to __.
​(Round to two decimal places as needed. Use ascending​ order.)