[{"_id":"1","region":"Auckland","anzsic_descriptor":"Agriculture","gas":"carbon diaoxide equivalents","units":"kilotonnes","magnitude":"carbon diaoxide equivalents","year":"2011","data_val":"764.3"},{"_id":"2","region":"Canterbury","anzsic_descriptor":"Agriculture","gas":"carbon diaoxide equivalents","units":"kilotonnes","magnitude":"carbon diaoxide equivalents","year":"2011","data_val":"6823.16"},{"_id":"3","region":"Bay of Plenty","anzsic_descriptor":"Agriculture","gas":"carbon diaoxide equivalents","units":"kilotonnes","magnitude":"carbon diaoxide equivalents","year":"2011","data_val":"1477.94"}]

db.collection.find({year:"2011",data_val:"764.3"})