City a Is a Modest Tourist Town, Which Means That

Short Answer

City A is a modest tourist town, which means that its population undergoes a seasonal variation. In January, it dips down to 4500 people. By July, with the warm weather, its population climbs to around 5500 people. This trend repeats every year. City B, on the other hand, is a small town not far from City A. Its population has been growing extermely rapidly ever since the arrival of several large industrial plants. There were only 4000 people living in City B on January 1, 2000, but its population has been growing by 9% every year thereafter. During which year did population of City A last equal the population of City B?