Distribution of all detected emissions in the CML− Φ_Io plane over the time interval 1990–2015 and the frequency range 10–40 MHz. In the bottom left panel, emission tracks are shown with the color code indicated in the top right. Tracks may overlap onto each other so that this figure provides qualitative information. Quantitative emission occurrence probabilities (without distinction of emission type) are plotted vs. the CML (top left) and Φ_Io (bottom right) in 5° bins.