You are an appraiser trying to estimate the stigma damage (uncertainty cost) of a contaminated property. You have estimated the unimpaired market value to be $930,000. The property is 15,500 square feet in size. You have indices of other contaminated properties of similar size to the subject property, and you have determined that $50 per square foot is an appropriate post-remediation market value for the subject. 

What is the stigma damage (uncertainty cost), expressed as a percentage?