The task is simple and straight forward so i am going to use this opportunity to provide some educational content along with RT charts and data to help you better understand how Churning works in Thorchain.

Churning Event refers to a situation where a node leaves or joins the network. validators numbers change, some shifting in Asgard vault and new node status in result.

Why and When a node will churn out?

There are some rules, like if you are the least active node in past 3 days you're out and can come back later, or bad behavior that accumulate negative point, other nodes banning you, having a better (more rune bonded) volunteer, and following on the node request itself.

what about churning in?

well anybody can run a node and join in thorchain network and the only requirement, quoted by their docs is: "Which nodes that are selected are purely by validator bond size. Larger bond nodes are selected over lower bond nodes"

Since Churning events happen periodically, you can't just add or remove a node. each node has a current status, which is Active, Disabled or Standby. Nodes that want to join the network are in "Ready" status, becoming "Active" when time comes. this is how this Churning event looks like over time:

For example, on week starting from March 14th 20 nodes joined the Thorchain network. On the same period 16 nodes turn from Active to Standby or Disabled Status as Chart below suggests.

It is obvious that number of nudes are increasing slightly overtime since churn in events are happening more than Churn outs.