Suppose \(r^{}_{}\) is a real number for which $$\left\lfloor r + \frac{19}{100} \right\rfloor + \left\lfloor r + \frac{20}{100} \right\rfloor + \left\lfloor r + \frac{21}{100} \right\rfloor + \cdots + \left\lfloor r + \frac{91}{100} \right\rfloor = 546.$$ Find \(\lfloor 100r \rfloor\). (For real \(x^{}_{}\), \(\lfloor x \rfloor\) is the greatest integer less than or equal to \(x^{}_{}\).)

(第九届AIME1991 第6题)