You need something which collects that information and aggregate over time. This is basically what XPack does behind the scene.

Note that monitoring in x-pack is available for free with the basic license.

Anyway, have a look at:

* https://www.elastic.co/guide/en/elasticsearch/reference/5.6/indices-stats.html
* https://www.elastic.co/guide/en/elasticsearch/reference/5.6/cluster-nodes-stats.html

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