Published data on the rise in hospitalizations of children and young adults due to asthma in four countries during the 20th century: asthmatics in the United Kingdom [A, See Ref 34]; children with asthma at the Medical College of South Carolina [B, See Ref 35]; children in Australia, New Zealand, Canada and the USA [C, See Ref 36]; and Finnish army recruits [D, See Ref 27]. All figures are used with permission but have been colorized differently than the original source material.