@Silvio6 You can validate it on the lines of the following expression
toString((indexOf(serializeList([
"2026-01-02",
"2026-01-05",
"2026-01-06",
"2026-01-07",
"2026-01-08",
"2026-01-09",
"2026-01-12",
"2026-01-13",
"2026-01-14",
"2026-01-15",
"2026-01-16"], "", false),"2026-01-06"))/(length...