CREATE TABLE table_4712 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

When North Melbourne played as the away team, what was the crowd numbers?
SELECT "Crowd" FROM table_4712 WHERE "Away team" = 'north melbourne'
SELECT "Crowd" FROM "table_4712" WHERE "Away team" = 'north melbourne'