To, the following macro should do your job:

Sub InsertRows()

StartRow = 2 'Change the 2 to the row actual data start
DataColumn = 5 'Change the 1 to the column where your data is

i = StartRow + 1
While Cells(i, DataColumn) < ""
If Cells(i, DataColumn) < Cells(i - 1, DataColumn) Then
Cells(i, DataColumn).EntireRow.Insert
i = i + 1
End If
i = i + 1
Wend
End Sub


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To run it:
Alt+F11 for the VB editor
menu command Insert | Module
Paste the code above

From Excel: Alt+F8