CREATE TABLE table_23151 ("LGA Name" TEXT, "Area  ( km 2  ) " FLOAT, "Census 2006 population" FLOAT, "Administrative capital" TEXT, "Postal Code" FLOAT)

How many areas (km 2) have 151511 as the census 2006 population?
SELECT COUNT("Area (km 2 )") FROM table_23151 WHERE "Census 2006 population" = '151511'
SELECT COUNT("Area (km 2 )") FROM "table_23151" WHERE "Census 2006 population" = '151511'