Calculated Columns

The formula of the custom column "No." is ="TR"&TEXT(Created,"yymm")&REPT("0",5-LEN(INT([ID])))&[ID] I had hoped, that user would add records and the view would show "TR070200001", "TR070200002", "TR070200003" etc, as the ID increments. However what the user was getting is "TR07020000", "TR07020000", "TR07020000". The formula is only calculated if I go into Modify Settings and Columns, Modify this ID column, and click Save.  

 

The problem is that calculated fields are only calculated and stored when saving an item...

So how should I do instead?