select
    pay_ability as pay_ability,
    concat (round(count(overdue_days) / count(1) * 100, 1), "%") as overdue_ratio
from
    loan_tb l,
    customer_tb c
where
    l.customer_id = c.customer_id
group by
    pay_ability
order by
    count(overdue_days) / count(1) * 100 desc