Percent of EU and US sites combined in each trend type (e.g., 0, 1a, 1b, etc.) with trends in (a) 6-month 12-h W126, (b) 6-month 12-h daily average, and (c) SOMO10. Summarized results from Lefohn et al. (2017). Trend Types 5, 6, and 8 did not occur and Trend Type X infrequently. DOI: https://doi.org/10.1525/elementa.279.f10