I just read the axes, maybe I'm actually wrong about what it means, and remembered other stuff I've seen on the Replication Crisis.

Ah, thanks for digging into the actual paper and providing that context.

SimpleStacker

When people do attempt to replicate results in econ, they're more often able to do so than in other social sciences. That may actually be the reason there are fewer replication attempts: the juice isn't worth the squeeze.

charts_and_maps

Replication rates across the humanities

Scoresby

This chart is just replication attempts. 

When people do attempt to replicate results in econ, they're more often able to do so than in other social sciences. That may actually be the reason there are fewer replication attempts: the juice isn't worth the squeeze.