Q19. How often do customers come? Customers per visit bucket.   [6 row(s)]
bucket                 | customers | bills
-----------------------+-----------+------
0 (no visit this year) | 3         | 0
1                      | 18        | 18
2-5                    | 72        | 255
6-12                   | 85        | 753
13-25                  | 52        | 941
26+                    | 26        | 986
