CREATE TABLE table_13690 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Attendance" TEXT)

What is the attendance when the opponent was the Houston Oilers?
SELECT "Attendance" FROM table_13690 WHERE "Opponent" = 'houston oilers'
SELECT "Attendance" FROM "table_13690" WHERE "Opponent" = 'houston oilers'