Time-of-year/time-of-day (F-UT) plots of: (a) the am index, 〈am〉_F,UT averaged in the 288 F-UT bins used in Figure 8; (b)–(l) the quantiles of the am/〈am〉_all distribution in each F-UT bin: (b) q(0.1); (c) q(0.2); (d) q(0.3); (e) q(0.4); (f) q(0.5); (g) q(0.6); (h) q(0.7); (i) q(0.8); (j) q(0.9); (k) q(0.95); and (l) q(0.99). All finalised am data are used which are from 1959 to 2017, inclusive.