CREATE TABLE table_33140 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Game site" TEXT, "Attendance" TEXT)

What was the date when the attendance was 77,918?
SELECT "Date" FROM table_33140 WHERE "Attendance" = '77,918'
SELECT "Date" FROM "table_33140" WHERE "Attendance" = '77,918'