CREATE TABLE table_57192 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

How big was the crowd when the opponent was essendon?
SELECT SUM("Crowd") FROM table_57192 WHERE "Away team" = 'essendon'
SELECT SUM("Crowd") FROM "table_57192" WHERE "Away team" = 'essendon'