Increment numbering: But in the order they are inserted

[FredSmith99]

Entering "data sets" into my document I need to ID them: I want this ID to be incremented "MaximumExistingID + 1" every time I insert a new data set. The key is that I do not want already inserted ID's to change (e.g. if I insert a new ID in the very beginning of the document).



All fields and settings I have tried, keep changing the numbers, incrementing them from the beginning to the end of the document. Any hint is welcome. Thanks!