SQL & PL/SQL

Hi,

I have a table as TFORM_RESULTS. And a column VANSWERS in that table. I keep the answers in that column as like "12:3:5:18". Simply my table data is like this:

TFORM_RESULTS

ID      VANSWERS     NFORM_ID 
1       12:3:5:6:7       2
2       13:2:3:2:4       2
3       10:8:1:3:4       2
4       19:4:6:3:7       2

The reason that i keep data un-normalized is maybe VANSWERS may change. In this example we have 5 answers but for NFORM_ID = 6 we may have 8 answers. But for the same FORM_ID we have equal answer count.

I would like to get the average of this answers as like this:

AVG 
13,5:4.25:3,75:3,5:5,5

Is there a simple way to get average as like this? I use APEX_UTIL.STRING_TO_TABLE to parse the column. There maybe simple solutions.

Thanks.

yvz