List.Sort(
    {100, 200, 0, 5, null},
    (x, y) => Value.Compare(x, y) * (if List.ContainsAny({x, y}, {0, null}) then -1 else 1)
)

cnt = List.Count(transfor_col ),
emp_rows = Table.TransformColumns(tab, List.Transform(transfor_col, (x)=> { x , each if _ = null then 1/ cnt else _, Percentage.Type }))

let
    Source = Excel.CurrentWorkbook(){[Name="data"]}[Content],
    result = (
        (group) => #table(
            group[Column1], 
            List.Zip(group[Column2])
        )
    )(Table.Group(Source, "Column1", {"Column2", (x) => x[Column2]}))
in
    result

let
    source = Excel.CurrentWorkbook(){[Name="Таблица1"]}[Content], 
    idx = Table.AddIndexColumn(source, "idx", 4, 1), 
    result = Table.TransformColumns(idx, {"idx", (x) => Number.Mod(x, 4) + 1})
in
    result