ServiceNOW Dashboard issues

HI I have a requirement for a dashboard to show closed incidents + closed tasks in one dashboard by assigned group/assigned to broken down by month. I am able to get the query to include past 12 months but can it be broken down according to month? Also is there a way to report on both tasks and incidents within the same dashboard?

I did create a dashboard with 12 months. I do not know how to break it by month.

You can use the Drill-Down method to create a dashboard drilldown, Put the Months in a table column and in total sum, put that in the graph.You can define a report drilldown to enable reporting users to view subsets of the report data. When you define a report drilldown, it applies only to the report for which you define it. Procedure

• Navigate to All > Reports > View / Run.
• Select the report you want to add a drilldown to.
• Click the Show report structure icon (Show report structure).
• A badge on the Report structure icon displays the number of defined drilldowns.
• Click the Add drilldown icon (Plus sign button)
• Enter a Title for the drilldown and click Next.
• Select the chart Type to display the data and click Next. See Creating reports.
• The drilldown chart type can be different than the parent report.
• Configure the drilldown report the same way you would configure any other report. Configuration options depend on the selected drilldown report Type.
• Click Save drilldown. Result

The user can drill down from the top-level report to the specified drilldown report visualizations. Can follow the link - ServiceNow Docs