Fig. 2.

Geographical distribution of incidence studies. 39 studies [15–53] reported incidence globally. Varying tiers of regional observation with some cross-coverage were reported, from municipal to national levels. Study targets, including their administrative level if not specific, consisted of, from approximately West to East longitude: Oregon, Oakland, Ontario, Rochester, Olmsted County, Atlanta, Nova Scotia, Prince Edward Island, Iceland, Faroe Islands, United Kingdom, Navarre, Gironde, London, Germany, Heidelberg, Mannheim, Altenburg District, Denmark, Kiel, Slovenia, Uppsala, Vasterbotten County, Huddinge, Helsinki, Uusimaa County, Oulu, Lapland, south Israel, Kazakhstan, Singapore, Taiwan, Taipei, South Korea, Nagasaki Prefecture, Fuchu City, Miyagi Prefecture. a World map with national boundaries, adapted from [69]. Countries highlighted correspond to sites in which incidence studies were performed. b Bar chart of number of incidence studies published by country. c Bar chart of number of incidence studies published by continent. No studies were identified from South America, Africa, or Oceania