How to filter by the hour?

So I have a 3 months worth of dataset comprises of 3 columns: Date, Time and Calls_Offered.

My objective is to analyze on which  particular hour is the busiest (most Calls_Offered) so we can identify which hour we can add resources and which hour we'll get resources from. 

Since i have to plot the hours and calls_offered first on a column chart, I Merged the date and time so now I have 2 columns left: DateTimeMerge, Calls_Offered. but when i try to visualize it on a stacked column chart, the minimum I can get is by the day. 

Is there a better way to do this?