you can create a calculated field that sums up all open tickets up until the date specified via parameter:
if isnull(date_closed) = true
and date_opened <= parameter_date then ticket_id
This way you count all the open ticket ids from the beginning of your data set (or the beginning of the year when you filter the view by the date_opened = 2016, for example) up until the parameter value.
Let me know if that helped.
Thanks Fabian. It helped. However, they wanted to add granularity as well.
When they Select The granularity which will have options like "Day","Week","Month" The parameter should display the corresponding categories and the calculations should reflect cumulative open count