The life table is the universally accepted demographic model for structurally and completely describing a population's experience of mortality and providing comparative measures for life expectancy. The model used to construct the life table assumes that an initial cohort of 100,000 live births is subject to the same sex and age specific death rates experienced by a real population during a specific period of time. The life tables using five-year data.
Life expectancy at birth is interpreted as the number of years that, on average, a generation of live births can expect to live if the mortality conditions do not vary in the future. Life expectancy at 65 years is an estimation of the average number of years that the population of this age can expect to live if the mortality conditions for the specified year or period remain constant.