rolling average by half hour

hi v-jiascu-msft

thanks for helping me. But i'm not trying to calculate the average for the last 30 mn.
So here is what i mean by "every 30 mn" : 
here is my data : 

as u can see, every 5min, i get a new ligne in the table. But i need to make a graph with the average per 30mn. 
So in the exemple bellow, i need to make the average for the data with the red line (30mn), and another average for the date with blue line (30mn), and so on.

Without average, i end up with a graph with so much irrugularity as the one on bellow. I made an average per hour.

Now i want to make the average per 30mn.
Hope i was clear this time, and sorry for waisting your time
Hope you can help me out with this.