Q14, MySQL/MariaDB version: DATE_ADD(... INTERVAL n HOUR).   [12 row(s)]
Service_id | finished_bills | on_time | on_time_pct
-----------+----------------+---------+------------
S0009      | 126            | 92      | 73.0
S0008      | 165            | 128     | 77.6
S0010      | 45             | 37      | 82.2
S0012      | 74             | 61      | 82.4
S0011      | 122            | 102     | 83.6
S0005      | 64             | 55      | 85.9
S0001      | 1343           | 1173    | 87.3
S0004      | 157            | 140     | 89.2
S0007      | 77             | 69      | 89.6
S0006      | 80             | 74      | 92.5
S0003      | 254            | 247     | 97.2
S0002      | 402            | 401     | 99.8
