Table:
text: 2008 St Kilda Football Club season
Home and away rounds
Home and away rounds
Round St_Kilda_Saints Opposition Their_Score Margin
13. (H) 10.5 (65) Fremantle 8.9 (57) 8
14. (A) 12.12 (84) North Melbourne 9.15 (69) 15
15. (A) 18.11 (119) Carlton 12.15 (87) 32
16. (H) 18.11 (119) Hawthorn 13.11 (89) 30
17. (A) 12.14 (86) West Coast 15.13 (103) 17
18. (H) 14.17 (101) Port Adelaide 14.9 (93) 8
19. (A) 12.11 (83) Collingwood 14.13 (97) 14
20. (A) 17.10 (112) Fremantle 9.15 (69) 43
21. (H) 13.17 (95) Adelaide 6.11 (47) 48
22. (A) 21.21 (147) Essendon 5.9 (39) 108

Question: What is the average margin a round of 16 2008 St Kilda Football Club has?