What the standard basket has cost at each chain, day by day

Recorded totals, not a reconstruction: each point is the figure this API published that day, and the last point of every series is the total /v1/insights/basket returns right now. Only chains that stock the whole basket appear, because a total over fewer lines is smaller for carrying less and is not comparable with the rest. Days with no record are absent rather than interpolated, so a step in points is always a movement between two published totals. History begins 2026-08-16; watchingSince is null before anything was recorded.