Default Dashboard: Google Ads Clickthrough Rate (CTR)
Definition of "Clickthrough Rate (CTR)":
The percentage of time people saw your ads and performed an inline link click.
Label: CTR (Link Click-Through)
Calculation: Inline Link Clicks divided by Impressions, bounded by some time period
MVC Scope: This will only be at the account level.
https://developers.google.com/adwords/api/docs/appendix/reports/ad-performance-report#ctr