how to get the user retention rate per month in last 1 year.

[cheriemilk]

Hi team, 

I have a stats requirement to get he user retention rate that visit a module per month in last 1 year.

Detail Requirement to stats:

step1. find the distinct users that visit a module in 2020, January

step2. go to 2020, February and find  the number of users in  step1 visit the module again

step3. go to 2020, March and find the number of  users in step2 visit  the module again

step4. go to 2020, April and find ....

.....

2020, December and find ...

Log sample in splunk and how can I write the query to get the expected user retention rate?

2021-01-19 06:00:38,668 PLV=REQ CIP=0.0.0.0 CMID=test CMN="testCompany" UID=testUser AGN="[Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36]"  module=SUCCESSION 

[ITWhisperer]

| eval month=strftime(_time, "%m")
| stats first(_time) as visit by month, UID, module
| sort visit
| streamstats count by UID, module
| where count = month 

This assumes you are starting from January so counts will be 1 in January, 2 in February, etc. if the user has visited the module at least once in all previous months.