I'm not sure if there is more available via the API, but in the dashboard the closest I know of is going to Network Wide>Traffic Analytics then you can sort the result by clients column. Note: This includes application data as well so it won't just be websites but I figure it would be equally interesting.
Adam R MS | CISSP, CISM, VCP, MCITP, CCNP, ITILv3, CMNO
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