What do you think of the following top-level summary Google analytics about usage for SageMathCloud, SageMath.org, SageCell server, and sagenb.org websites during the last month? In the figure below, salvus=SageMathCloud and aleph.sagemath.org=SageCell server.
A measure of usage is the "expected total time users spent on the sites", by which I mean the number of sessions times the average session time, in days.
SageMathCloud 996.0
SageMath.org 145.9
SageNB 113.6
SageCell 94.8