The spike at weeks 111-114 is a bug due caused due to multiple weeks with no run. This will be fixed... eventually.
Retention graph
Retention is how much people that were part of the community at a given week stayed in the following one.
Since total amount of users is a changing number, it is meaningful to represent this number as a percentage of the total,
instead of the simple amount of people.
There is a notable upwards trend, which makes sense, since you can think of people as sediments going through a river.
Most of them flow away, but some stay. Maybe for good, maybe for a while.
But the key is that after some time, the sediments start accumulating and become something bigger.
If given enough time, they can create a delta or a small island, and this becomes a solid community.