Second thyroid cancer is treatable.
Third, IF your chart is correct, then you have proven that the study you posted earlier is incorrect. IF the study you posted was correct then that chart should read three times higher than it is.
And finally, I disagree with the study you posted.
Radioactive iodine can not only travel hundreds of miles on the winds, but also still remain health threatening even as other radioisotopes are becoming dispersed and diluted along with it and their likelyhood of causing harm diminishes. It is often overlooked that while there will also be many other dangerous radioisotopes released along with radioiodine, if they are inhaled or ingested they are normally dispersed throughout a body and pose less of a risk than if they were to be concentrated into one small specific area of the body, like radioiodine is in the thyroid gland. As a plume or cloud of radioactive isotopes disperses with the wind its danger also diminshes, but always much less quickly so for radioiodine because whatever little there is that's inhaled will always be concentrated into that small space of the thyroid gland.
NUREG-1633 points out an increase in thyroid cancer caused by radioiodine from Chernobyl...
"...was detected in Belarus, Russia, and Ukraine. Notably, this increase, seen in areas more than 150 miles (300 km) from the site, continues to this day and primarily affects children who were 0-14 years old at the time of the accident...the vast majority of the thyroid cancers were diagnosed among those living more than 50 km (31 miles) from the site."
The updated (1999) World Health Organization (WHO) Guidelines for Iodine Prophylaxis following Nuclear Accidents states in its abstract regarding thyroid cancer caused by the Chernobyl disaster:
"This increase in incidence has been documented up to 500 km from the accident site."
...and therefore...
"...that stockpiling (KI or KIO3) is warranted, when feasible, over much wider areas than normally encompassed by emergency planning zones, and that the opportunity for voluntary purchase be part of national plans."
Also, regarding the treatability of thyroid cancer and thus implying it's perhaps not that big a deal, if that's what you had meant to suggest, the 1000 who die from it every year here in the USA might not share your view.
Bottom Line: Ingested or inhaled radioactive iodine (radioiodine) persists in the body and concentrates in the thyroid. (Excess iodine in the blood, either radioiodine or stable iodine, is quickly eliminated from the body, but only after the thyroid has become saturated with one or the other type of iodine.) Even very small amounts of radioactive iodine, because it is retained in the small space of the thyroid, eventually will give such a large radiation dose to thyroid cells there that abnormalities are likely to result. These would include loss of thyroid function, nodules in the thyroid, or thyroid cancer. The most likely to see the worst effects, in later life, are the youngest children. (Many of the Chernobyl thyroid cancers appearing in the former Soviet Union among young people today were just children less than five years old at the time of the accident. Experts now contend that as high as 40% of the nodules are cancerous with 5 to 10 percent of the cancers fatal.)
Every year researchers are discovering more from Chernobyl as its legacy continues to reveal itself. According to the World Health Organization, that disaster will cause 50,000 new cases of thyroid cancer among young people living in the areas most affected by the nuclear disaster. Researchers have also found that in certain parts of Belarus, for example, 36.4 per cent of children, who were under the age of four at the time of the accident, can expect to develop thyroid cancer.
No other radioactive isotope expelled from Chernobyl is racking up anywhere near these numbers well away from ground zero.
Yes, Potassium Iodide (KI) and Potassium Iodate (KIO3) only protect you from one of many isotopes that'll be released, but for less than 25 cents for a daily dose, that's pretty cheap insurance for the one expected to cause the greatest number of casualties downwind and well away from ground zero, IMO.
-Shane