I know it's cells for % male and % female that's missing. What I wrote is that if it were filled in, it would be 100% because what that table shows is percent by age *within the sex category.* If they were to fill the top of the column in with, for example, 49.5% percent male and 50.5% female, that would be mixing and matching denominators within the column. Changing denominators within column would lead readers astray on how to interpret the values farther down the column which are NOT sex percent of total population in a given age group but rather are % distribution by age *within the sex category.*
If you are interested in percent male/percent female, rather than age distribution, use a different table: DP05.