CREATE TABLE table_35471 ("Week" FLOAT, "Date" CLOB, "Opponent" CLOB, "Result" CLOB, "Game site" CLOB, "Attendance" FLOAT)

what week number was at memorial stadium?
SELECT AVG("Week") FROM table_35471 WHERE "Game site" = 'memorial stadium'
SELECT AVG("Week") FROM "table_35471" WHERE "Game site" = 'memorial stadium'