Create three fields:
- Year. [type: calculation; number=Year(DOB)]
- Month [type: calculation; number=Month(DOB)]
- Count [type: summary; Count of:DOB]
Now create a report with a subsummary part for year, and another subsummary part for month. Put the Count field in the Month subsummary part, find all records and sort them by Year, then Month.
One question more,
How to make chart were view litter born different years?month?