sum field in table

hallow

i have table with emp miss for month and i wont to add another line with sum of miss days for month how i can do that ?

kostl month1 month2 month3 month4 month5 month6

1000-10 532 456 503 453 522 500

1000-11 23 20 21 19 22 20

for this table ccmissdays i wont to add line with bold (sum)

kostl month1 month2 month3 month4 month5 month6

1000-10 532 456 503 453 522 500

1000-11 23 20 21 19 22 20

<b>555 476 524 472 544 520</b>

Best regards