Unpivot Multiple Coumns

I've mocked up a sample with the solution here. Please paste into the advanced editor and follow the steps:  

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WclTSUUoEYkMDIJEExMYGSrE60UpOUHEjmLgJUDwWAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Item = _t, pcsplit_1 = _t, prctr_1 = _t, pcsplit_2 = _t, prctr_2 = _t]),
    #"Unpivoted Other Columns" = Table.UnpivotOtherColumns(Source, {"Item"}, "Attribute", "Value"),
    #"Split Column by Delimiter" = Table.SplitColumn(#"Unpivoted Other Columns", "Attribute", Splitter.SplitTextByDelimiter("_", QuoteStyle.Csv), {"Attribute.1", "Attribute.2"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Split Column by Delimiter",{{"Attribute.1", type text}, {"Attribute.2", Int64.Type}}),
    #"Pivoted Column" = Table.Pivot(#"Changed Type1", List.Distinct(#"Changed Type1"[Attribute.1]), "Attribute.1", "Value"),
    OptionalRemove = Table.RemoveColumns(#"Pivoted Column",{"Attribute.2"})
in
    OptionalRemove