Design a modular algorithm (flowchart and pseudo-code), code (C#) and test (desk check and test plan) a solution to solve the following problem:

The city of Ankh-Morpork held a special census to collect data on its residents. The file containing the results of the census is structured as follows:

FIELD DESCRIPTION DATA TYPE	 VALID VALUES

Age	 Numeric	 Greater than 0

Gender	 Character	 M, m, F, f

Marital Status	 Character	 M, m, S, s

District	 Numeric	 1 - 22

The fields in each record will be separated by a comma.

For example: 21, M, S, 1

The city has 22 districts. The census department wants to see a listing of how many residents are in each district, and a count of residents in each of the following age groups (for all the districts combined): under 18, 18 through 30, 31 through 45, 46 through 64, and 65 or older.