Q20. New customers per month (older ones counted as 'before').   [13 row(s)]
month          | new_customers
---------------+--------------
before 2025-10 | 110
2025-10        | 7
2025-11        | 8
2025-12        | 9
2026-01        | 17
2026-02        | 22
2026-03        | 20
2026-04        | 22
2026-05        | 7
2026-06        | 6
2026-07        | 5
2026-08        | 10
2026-09        | 13
