Here is the chart:
The number of rental operations for Splinterlands has been going up troughout the whole year. There are now services that provide card management for owners and these are probably making more operations.
Unlike some other Splinterlands operations that are not stored on the blockchain, for example battles, rentals are still recorded on the blockchain. Because of this they have now become number one operation that Splinterlands records on the blockchain and the number one operation on the chain itself that is using most of the RC these days.