You can issue the following commands:
SET,LAST !Read last set of result
ETABLE, ,S,1 !Store S1 data in element table
ETABLE, ,S,2 !Store S2 data in element table
ETABLE, ,S,3 !Store S3 data in element table
This will give you a sum of each table - S1, S2, and S3. Then you can add the same in excel.
For instance, sum of each S1, S2 and S3 will look like as indicated below and then you can further add them.