You are asking for Excel to create the 'missing' position values and then put a 0 in the column next to it. An automated way would require VBA, since Excel will not create data for you. The 'easier' way is for you to create the list of integers 1 to 18 (or whatever your max Position value is) in column C. Then in D1 use:
=IFERROR(INDEX($B$1:$B$18,MATCH(C1,$A$1:$A$18,0)),0)
and drag down the column