|Top Search Queries data in Google WMT|
The Search Queries page shows those Google Web Search queries that have returned URLs from your site. You can also see information about the pages on your site that were seen most often in search results (top pages). You compare daily averages for the selected period to daily averages for the previous period. Google Webmaster show the last 30 days of data by default, but you can set the date range for the report using the calendar selectors above the graph.
To help jump-start this year and make metrics for your site more actionable, Google WMT updated one of the most popular features (Search Queries data) in Webmaster Tools: data in the search queries feature will no longer be rounded / bucketed. This change will become visible over the next few days.
The search queries feature gives insights into the searches that have at least one page from your website shown in the search results.
The Search Queries Data report shows the following elements:
Top Data Queries:
CTR (clickthrough rate):
Read more about this update go on https://support.google.com/webmasters/answer/35252?hl=en