Datasets used in this study. Grey dots indicate SXR flares of ≥M1 class registered between September 1975 and June 2017. Purple squares, olive diamonds, and cyan pentagrams denote flares associated with SEP events with fluences of f₁₀₀ > 0, f₈₀₀ > 10³, and 10⁵ cm⁻², respectively. The brown line shows the smoothed international sunspot number (version 2). The horizontal bars on the top indicate the coverage of SXR, f₁₀ – f₁₀₀, and f₈₀₀ SEP data.