CREATE TABLE table_51915 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

How many people were in the crowd when the away team scored 15.18 (108)?
SELECT "Crowd" FROM table_51915 WHERE "Away team score" = '15.18 (108)'
SELECT "Crowd" FROM "table_51915" WHERE "Away team score" = '15.18 (108)'