To see a field’s summary, in List View, right-click on a column’s header. Hover over "Summary" and choose the type of summary you'd like to run.
If you'd like to set the default summary for a field on any page, right-click the field header and choose "Configure field..." where you can choose from the "Summary" drop-down to pick a default value, then choose “Update Field.”
When showing the Page Summary of a Status field, you can Calculate the Status Summary with a Percentage - Rounded or Percentage - Decimal.
Decimal display options can be configured via Language and Formatting in Site Preferences.
Default N/A (na) and Omit (omt) statuses are ignored in these calculations.