this is a little old but could be used for very approximate approximations: http://www.joelcomm.com/app_store_ranktosales_revealed.html http://www.joelcomm.com

this is a little old but could be used for very approximate approximations: http://www.joelcomm.com/app_store_ranktosales_revealed.html http://www.joelcomm.com/app_store_ranktosales_revealed.html