My little datapoint
Nexus 5x running Android 6.01 Data usage in the period
april 21st to may 20th
Total: 105MB
foreground:32,77
background:72,66
march 21st to april 20th
Total: 218MB
foreground:20,25
background:198
february 21st to march 20th
Total: 201MB
foreground:59,34
background:142...