DNA denaturation and renaturation - (May/02/2011 )

How can I calculate the % DNA denatured at 30 degrees after cooling from a higher strand seperation temperature such as 100 degrees as in the picture?

At 30 degrees (assuming Celsius here, not Fahrenheit) there should be very little DNA denatured - after all, in the cell, at 37 degrees C DNA is normally double stranded.