Hi, If your version is 2014 or later you can open your dfsu file by right click and Open with Data Manager. Then go to Tools > Calculate Statistics.
If your version is before 2014, you can change the settings to open your 'dfsu' file with Data Manager. In MIKE ZERO window go to File > Options > User settings > File Associations and change the editor for '.dfsu' from Data Viewer to Data Manager. Now open your file and go to Tools > Calculate Statistics.