The 100 million urban hukou residents, however, were fed by fixed food rations established by the central government, which declined to an average of 1500 calories per day at times but still allowed survival for almost all during the famine. An estimated 95% or higher of all deaths occurred among rural hukou holders. With the suppression of news internally, many city residents were not aware that mass deaths were occurring in the countryside at all. This was essential to preventing organized opposition to Mao's policies.