[ic] loop select drop down menu from delimited field

[Tom Luong]

I would like to loop a drop down menu. However, the column I want to loop
has several values delimited by a comma.
1,5,6,7
2,3
4,8,9

I would like the dropdown menu to show
1
2
3
4
5
... etc
instead of
1,5,6,7
2,3
4,8,9

this is the code I have so far,
<select name=mv_searchspec>
<option value=""> --Select One--
      [loop search="
         fi=products
         st=db
         rf=year
         tf=year
         un=yes
      "]
 <OPTION VALUE="[loop-code]"> [loop-code]
 [/loop]
</select>

any suggestion?
I guessing it may have something to do with index_delim or return_delim, but
I haven't been able to get it to work.

TIA,

tom