Awendak, isalan win edag wan ameriəaintan ən teɣare tan elan win 1990 asiknanen as andaran daɣ deden hanat magradan,izar magradan akalan taberat tan timusnawen nadinat diha ad ajit ən ɗeɗen tifnaz hulen, ɗeɗen tiwaɗnen jar 17% ad 30% ən imasaɣar ən magrad ɣur teɣarawen tiyaɗ.