Help Needed from Orion.IpSla.VoipOperationsICMPEcho

Hello,
The below syntax gives data as one result per day. How can I get it hourly to create a graph, thank you in advance

SELECT Summarydate, Operation_Name, AVERAGE_of_Avg_Round_Trip_Time
FROM Orion.IpSla.VoipOperationsICMPEcho
where Operation_ID= "768"