Which number should be used as a divisor for the percentage values?

Hello!

I need to create a bar chart for my BA.

I have three age groups. I would now like to display the number of people in each age group. I would like to use two columns: one with the number of participants in my survey, and one with the total population.

Should I use the sum of the total number of people as the base value for calculating the percentages or should I use the sum of the values ​​of the individual sums for each of the two columns (column A: sum of the total population; column B: sum of the participating people)

Thank you and best regards