How do I make a rolling weekly percentage?

[altinCamp]

I'm new to splunk, but I need to figure out how to count the number of error codes of a certain type over a rolling 7 day span going back to the start of the year. so from 01/01/2020 to current date of search. broken down into rolling 7 day averages... so if its Wednesday it goes back to Thursday of the previous week, if it thursday it goes back to friday of the previous week and it goes all the way back to the beginning of the year but broken out into 7 day periods.  Is this possible with Splunk? 

Error_Code = "x" | timechart count span = 1d is as far as i've gotten

[ITWhisperer]

Error_Code = "x" 
| bin _time span=1d
| stats count by _time
| autoregress count p=1-6
| eval sevendaycount=count+count_p1+count_p2+count_p3+count_p4+count_p5+count_p6