Looking to create a cumulative column in SAS - sas

Question

Example Dataset:
record_id admin_dt_1
1 June 7th 2022
2 August 25th 2022
3 August 23rd 2022
4 July 8th 2022
5 August 5th 2022
I would like my output to show in the first column September 1st...2nd...so on to 30th which I have done but I would like the second column to show the number of people eligible for each day in September. Eligible means anyone after 28 days from their admin_dt_1. I also want the column to be cumulative it should look something like this: Since there are 5 data points it should add up to 5 in the frequency column.
Date Frequency eligible
September 1st 3
September 30th 5
data dose2eligible;
set request;
/*create September 1st to September 30th date*/
do date= '01sep2022'd to '30sep2022'd;
output;
end;
format
date date9.;
run;
proc freq data=dose2eligible; table date; run;

Answer 1

You were very close. Count the number of days between admin_dt_1 and date, then create a 1/0 flag using the shortcut var = (boolean comparision):
eligible = (admin_dt_1 - date > 28);
data dose2eligible;
set request;
/*create September 1st to September 30th date*/
do date= '01sep2022'd to '30sep2022'd;
eligible = (admin_dt_1 - date > 28);
output;
end;
format date date9.;
run;
You can then count the number of eligible people on each date:
proc sql;
select date
, sum(eligible) as total_eligible
from dose2eligible
group by date;
quit;