On the X axis, I have Hours (event. timestamp)

On the Y axis, I want to have a graph with the maximum amount of cases that have happened. but on a day. ( So for example 1-01-2022 at 9 hours the count was 10 and on 2-01-2022 at 9 hours the count was 30, I want the output for 9 hours to be 30)

At the moment I use this to calculate the average

COUNT ( DISTINCT CASE WHEN "eventlog_T1"."ACTIVITY" = 'activity'' THEN "eventlog_T1_CASES"."cases" END )/

( COUNT ( DISTINCT Round_Day ( "eventlog_T1"."TIMESTAMP" ) ) )

Does any one has a suggestion how to get the maximum value on a day per hour