Table: t_1974_vfl_match_2
Columns: home_team
home_team_score
away_team
away_team_score
venue
crowd
date

Question: When the away team scored 18.13 (121), what was the largest crowd size?
SQL: SELECT MAX("crowd") FROM t_1974_vfl_match_2 WHERE "away_team_score" = '18.13 (121)'