The easiest way would be to use optimize. but if you don’t use Optimize you can query the history data. Either via the REST API or you could move the data from Camunda’s history tables to a reporting tool of some kind.
Thanks @ismael_adra. We are currently extending our APIs to do so.
As Niall mentioned, you can use the Optimize UI to create reports, and to get the data via API, we are extending the endpoints to powerful queries and a way to receive the result count per query (like “number of tasks a user completed last week”).