Count total number of values in a field of all nodes combined for a view
There is a module to assist with that: Views Field


  Allows field tables to be used as base tables with Views.


After you installed the module you need to visit the field setting on any content type that includes the field. Tick Expose as base table, then select all the columns to expose excluding revision_id.

Next create a view and at admin/structure/views/addat Show listbox you select the Field base table. This will now create a view on the field in question's base table.

Your view settings should have these settings:


Use aggregation: Yes
Fields: Entity Type (The entity type this data is attached to) with
Aggregation setting Count.


You can now add Relationship: Field tables: Field XXX => Node to get access to the nodes the fields are attached to and from there author etc.

ALTERNATIVE

Create a View of Content (ie nodes) showing fields. Set Aggregation to Yes. Remove sort Criteria, filter criteria and Pager. Add your field's delta (Delta - Appears in: node:xxx.) to the View fields with aggregation set to COUNT.