Groupby Maximum in Transform Data

I split the column, did a groupBy to get Max Year, (maintaining original data).

Then Expand the column and select the rows that match Max Year.

Then another GroupBy to get Total Cost

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjRQ0lEyBGJjAzALREQGGVoqxepgSBpBJIEUFklDU6ySJviMhUiiaDTCaiVUoxFWx6LrNMHiWDDPCId70CSR7IwFAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [AFE = _t, Major = _t, Minor = _t, Cost = _t, GL_YEAR = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"AFE", Int64.Type}, {"Major", Int64.Type}, {"Minor", Int64.Type}, {"Cost", Int64.Type}, {"GL_YEAR", type text}}),
    #"Split Column by Positions" = Table.SplitColumn(#"Changed Type", "GL_YEAR", Splitter.SplitTextByPositions({2}), {"GL_YEAR.1"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Split Column by Positions",{{"GL_YEAR.1", Int64.Type}}),
    #"Grouped Rows" = Table.Group(#"Changed Type1", {"AFE", "Major", "Minor"}, {{"MaxYear", each List.Max([GL_YEAR.1]), type number}, {"all", each _, type table [AFE=number, Major=number, Minor=number, Cost=number, GL_YEAR.1=number]}}),
    #"Expanded all" = Table.ExpandTableColumn(#"Grouped Rows", "all", {"Cost", "GL_YEAR.1"}, {"all.Cost", "all.GL_YEAR.1"}),
    Custom1 = Table.SelectRows(#"Expanded all", each ( [MaxYear] = [all.GL_YEAR.1])),
    #"Removed Columns" = Table.RemoveColumns(Custom1,{"all.GL_YEAR.1"}),
    #"Grouped Rows1" = Table.Group(#"Removed Columns", {"AFE", "Major", "Minor", "MaxYear"}, {{"TotCost", each List.Sum([all.Cost]), type number}})
in
    #"Grouped Rows1"

Let me know how you get on