Hi @juancure
When enabled, the Usage Statistics plugin will track the access to the article page, galley page/download, issue page and journal home page. This plugin considers the standard COUNTER. Thus the other visits, to other journal pages are not considered here.
The access is then logged in the files. Those log files are in your files folder, in the usageStats sub-folder. Those log files are then processed and the view counts calculated and saved in the DB table metrics. (First, the new log files are in the folder usageEventLogs. When being processed they are moved to stage, then to processing, and then either to reject or archive folder – depending on if any error occurred i.e. if the file was successfully processed.) .
For the graph that is displayed on the article view page, the information in the DB table metrics is used. Only the downloads of the article galley files are considered for the graph. In the current OJS version, this graph only considers the view counts from the current year. This will change with the next OJS release, so that the graph will consider the view counts from the last 12 months, s. Display usage statistics for last 12 months instead of for current year · Issue #3283 · pkp/pkp-lib · GitHub.
Thus, you could double check if everything is OK with the data in the DB table metrics, or with your log files. Maybe those other article files were not downloaded in this year?
See also this document for more information: https://pkp.sfu.ca/wiki/index.php?title=PKP_Statistics_Framework
Best,
Bozana