CREATE TABLE table_13724 ("Week" FLOAT, "Date" TEXT, "Opponent" TEXT, "Result" TEXT, "Attendance" FLOAT)

What's the week when the Green Bay Packers were the opponent and less than 57,966 were in attendance?
SELECT COUNT("Week") FROM table_13724 WHERE "Attendance" < '57,966' AND "Opponent" = 'green bay packers'
SELECT COUNT("Week") FROM "table_13724" WHERE "Attendance" < '57,966' AND "Opponent" = 'green bay packers'