Per-source-type analytics row

One analytics row per source type: the share of all citations in the window that came from sources of that type, with its change against the preceding period.

Fields

Field	Type	Description
source_type	string	The source classification this row represents.
used_percentage	integer	The share of all citations in the window that came from sources of this type.
used_percentage_change	integer	The difference in `used_percentage` compared with the equal-length period immediately preceding the window.