Nigeria? Heh... I give you Cuba. Monthly average salary 3902 pesos which, converted to USD, yield 31.2. It would take, what? 50 months?
https://www.xe.com/currencyconverter/convert/?Amount=3902&Fr...
The black market, or unofficial, rate is what everyone thinks about[2].
[1]: http://www.cubadebate.cu/especiales/2022/08/29/apuntes-sobre... [2]: https://eltoque.com/tasas-de-cambio-de-moneda-en-cuba-hoy
https://www.reuters.com/markets/us/cuba-more-than-quadruples...