There are several ways to filter your participants and create groups as described in the article on Creating a group of participants using filters.
The same way that administrators can filter by any other signup form question, with the year of birth option, admins can now filter by year with "on or after" or a "before" filter as shown below.
Combining both with the same year acts as a filter for that year alone.
Contact our support team if you need any further assistance via chat or email support@engagementhq.com