This process of cohort succession is thus increasing the average literacy rate of the population 60 and older over time. In addition, Phnom Penh elderly represent a larger share of the SEC sample than of the national population of elderly and, as indicated above, since the literacy level of Phnom Penh elderly is above the national average, this also has the effect of raising the average literacy level compared to nationally representative census results. However when tabulations of SEC are limited to persons 66 and older to correspond to the cohorts who were 60 and older in 1998, the.
