You can't export all graphs at once, but you can export individual data points from reports.
To export specific data points from Statistics into excel, go to 'Reports' and click on any bar, point on a graph, or number in any graph you would like to export.
For the Dashboard, just simply click on any number.
That'll give you a popup showing the list of all of the data included in that number or point on the graph. In that popup, click the three dots in the top right corner, then select 'Export statistics results':
Then just select the file type and you're done.