See this blog post for a solution: Creating Reference Dates for Intervals.
Add something like this to the script in the Data Editor.
MonthStart(Admission, IterNo()-1) as Month
MonthStart(Admission, IterNo()-1) <= Alt(Release, Today())
You can then use the new Month field as dimension and count(Name) as measure in a chart.
Thank you for the quick reply. It helps a lot but somehow I do not get the while loop working correctly. It seems to loop over the first name only, so I get all months for Peter until today, but Maria and Tom are missing. Is there a typical error I be doing or are more details needed to find a solution?
After some tries it is now working. Please find the final script (the part which I changed) below and the .xls and .qvf file attached. Thank you for the support!
(ooxml, embedded labels, table is Sheet1)