After performing a search, click on a blue data marker or click Filter Results on the right-side panel. In the list of Search Results, highlight a data series by clicking on the row. To highlight more than one data series, hold down the CTRL key and click on multiple rows. Once the data series are highlighted in blue, click Select Action and choose Export selection. If you are signed in with your Google account, two exporting options will appear: (1) Export Selections in combined file (2) Export each selection in a separate file. The data series will automatically download to your local computer as a CSV file. For larger files that may take longer to export, check the status of the export by clicking on the Exports button in the top right as shown below.
The Exports tab is shown below.