Counter for one unique expression for every row

https://drive.google.com/file/d/1cBpewQpejSBMtK2Pvk-_-t9pH0ORh3Ue/view?usp=sharing 

see the Pbix in the link. Outline of the solution:

- add an index column to the table;

- duplicate the table (table (2);

- filter table (2) on "Date";

- add an index on tabel(2) (starting at 1);

- merge table and table (2) on index;

- fill the index column down;

Good luck,

//JW

Here is one way to do it in the query editor.  To see how it works, just create a blank query, go to Advanced Editor, and replace the text there with the M code below.  Note that the Rename and Trim steps were only needed as the data you pasted had leading/trailing spaces.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckksST20ADtU0lFCF1IwMjAy1DMw1jMwUYrViVZyzs8tSMyrxKNXISS1uCQZogysxTOvuKSoNDc1r0SjWBNdMULSkBTFRjDHgDjFONwCdolCMkQRWAPZnjcjw/NGNPY9kYqNiQqq/JKM1CJEWMUCAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"voteOptionText  " = _t, #"  voteAnswer" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"voteOptionText  ", type text}, {"  voteAnswer", type text}}),
    #"Renamed Columns" = Table.RenameColumns(#"Changed Type",{{"voteOptionText  ", "voteOptionText"}, {"  voteAnswer", "voteAnswer"}}),
    #"Trimmed Text" = Table.TransformColumns(#"Renamed Columns",{{"voteOptionText", Text.Trim, type text}, {"voteAnswer", Text.Trim, type text}}),
    #"Added Custom" = Table.AddColumn(#"Trimmed Text", "DateForFillDown", each if [voteOptionText] = "Date" then [voteAnswer] else null, type text),
    #"Filled Down" = Table.FillDown(#"Added Custom",{"DateForFillDown"}),
    #"Grouped Rows" = Table.Group(#"Filled Down", {"DateForFillDown"}, {{"AllRows", each _, type table [voteOptionText=text, voteAnswer=text, DateForFillDown=text]}}),
    #"Added Index" = Table.AddIndexColumn(#"Grouped Rows", "Index", 1, 1, Int64.Type),
    #"Expanded AllRows" = Table.ExpandTableColumn(#"Added Index", "AllRows", {"voteOptionText", "voteAnswer"}, {"voteOptionText", "voteAnswer"}),
    #"Removed Columns" = Table.RemoveColumns(#"Expanded AllRows",{"DateForFillDown"})
in
    #"Removed Columns"

Pat