A data frame with one row per country and age group. For each country there are seven age groups. It contains columns country_code
, name
, age
and one column per five-year time interval (i.e., from 1 July in year t to 1 July in year t+5 such as the period 1950-1955 refers to the period 1950.5-1955.5 and the mid of the period is 1953.0).