Aggregate fields.

[Proto definition ![GitHub](https://developers.google.com/site-assets/logo-github.svg)](https://github.com/googleapis/googleapis/blob/master/google/ads/googleads/v26/enums/keyword_plan_aggregate_metric_type.proto)

| Enums ||
|---|---|
| ## `DEVICE` | The device breakdown of aggregate search volume. |
| ## `UNKNOWN` | The value is unknown in this version. |
| ## `UNSPECIFIED` | Not specified. |