We want to segment customers by payment behavior. There's a monthly statement table that records each customer's statement balance and actual payment amount every month; for example, customer 101 paid in full every month for the past six months, while customer 102 only paid part of the balance in four of those months. Write SQL to classify customers as transactors, revolvers, or inactive, and count how many fall into each group.

我们想按还款行为给客户分群。有一张月度账单表，记录每个客户每月的账单金额和实际还款金额；比如客户101过去六个月每月都全额还清，客户102有四个月只还了一部分。请你用SQL把客户分成交易型、循环型和不活跃三类，并统计每类人数。