In contrast, the incidence proportion can be calculated as 16 â 2,100 = 7.6 cases per 1,000 population during the four-year period, or an average of 1.9 cases per 1,000 per year (7.6 divided by 4 years).
The Costs. Minimum Cost: Approximately $.50 per square foot. Maximum Cost: Approximately $2 per square foot. The size of roofs vary immensely from a standard, urban roof measuring about 800-square-feet to suburban roofs, which often range above 1,500-square-feet.aximum Cost: Approximately $2 per square foot. The size of roofs vary immensely from a standard, urban roof measuring about 800-square-feet to suburban roofs, which often range above 1,500-square-feet.
The national average for a 3,000 square foot asphalt shingle roof is roughly $11,500. The actual cost varies. Like anything, urban areas are generally more expensive than rural areas. The average cost of a roof in New York, for example is close to $15,000.The same roof replacement in Georgia or the deep south will probably cost less than $9,000. The Midwest is also less expensive. Homeowners in Wichita, Kansas pay an average of $10,000.ven within the same general region of the country, prices vary drastically. The average cost of a new roof in the Carolinas hovers around $7,000 while Atlanta homeowners pay around $10,000.