Charge % for a 1 year, 6 month, and month to month rental

[Amy Barriault]

How  much more should I charge if a renter wants to renew a year long lease and convert it to a 6 month or month to month lease? Any info you would be willing to share on how much mark up % for a 6 month or month to month lease would be helpful. 

Many thanks,

Amy