In the linked article it actually shows max concentrations at 500. So for those areas it (basically) really is your original number. It's further telling with

In the linked article it actually shows max concentrations at 500. So for those areas it (basically) really is your original number. It's further telling with this quote: > Iowa and Illinois, where the most corn and soy crops are grown, accounted for 15% of national usage Which means some states heavy skew the results and many, many areas of the country are below 100 or near 0.