The parameters of the log normal energy consumption distributions are calibrated in each country from available data, most often food balance sheets for the average energy availability and household surveys for the variance. The percentage of undernourished population (also referred to as the chronically hungry) is measured as the area under food consumption distribution curve below the minimum requirement cut-off point measured in kcal/person/day, which is specific for each country. The FAO uses a related indicator to monitor the Millennium Development Goal of halving the number of undernourished. Another related Food Security Indicator in the FAO statistics is the depth of food deficit, which measures (in kcal) the gap between the average dietary energy consumption of the undernourished population (food-deprived) and the average dietary energy requirement, scaled up to the population as a whole by the total number of food-deprived persons. This indicator captures both the availability and access dimensions of food insecurity.