Substract Production from the last year

Hi OscarSuarez10,

here we go.

At the begining I prepare some test data and create a column Year. The rest is commented in code.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WckksSVXSUQooyk8pTS7JzM9TitWJVspKzNM11DUyMLQEyhkaGIAF01KTEIJGUMHcxKLkDF0FQ10FqIQxVCKxoCgzB6HeBCoMM9nIAMkQmMlgQWMsJoMlTDBMBguboxtiCHEzUDQWAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", type text}}),
    #"Promoted Headers" = Table.PromoteHeaders(#"Changed Type", [PromoteAllScalars=true]),
    #"Changed Type1" = Table.TransformColumnTypes(#"Promoted Headers",{{"Date", type date}, {"Production", Int64.Type}}),
    Year = Table.AddColumn(#"Changed Type1", "Year", each Date.Year([Date])),
    
    // till now data preparation
    
    // group by Year and get min and max of production per year
    #"Grouped Rows" = Table.Group(Year, {"Year"}, {{"MinOfYear", each List.Min([Production]), type number}, {"MaxOfYear", each List.Max([Production]), type number}}),
    // add an index columns
    #"Added Index" = Table.AddIndexColumn(#"Grouped Rows", "Index", 0, 1),
    // create column maxOfLastYear by reading the previous row
    #"Added MaxOfLastYear" = Table.AddColumn(#"Added Index", "MaxOfLastYear", each try #"Added Index"{[Index] -1}[MaxOfYear] otherwise 0, type number),
    // calculate the difference
    #"Added Difference" = Table.AddColumn(#"Added MaxOfLastYear", "Difference", each if [MinOfYear] = [MaxOfYear] then [MaxOfYear] - [MaxOfLastYear] else [MaxOfYear] - [MinOfYear])
in
    #"Added Difference"