As of the latest available data, there are approximately 20,000 ninth-graders in Xuzhou, USA. This figure is based on the enrollment numbers from the Xuzhou Public Schools District, which encompasses all public schools in the city. The number of ninth-graders can fluctuate annually due to various factors such as demographic shifts, birth rates, and changes in school policies. However, the consistent growth in the student population has led to a steady increase in the number of ninth-graders over the past decade.

The reason for the significant number of ninth-graders in Xuzhou can be attributed to several factors. Firstly, Xuzhou has experienced rapid economic growth, attracting a large influx of families from other parts of the country. These families often seek better educational opportunities for their children, leading to an increase in the student population. Additionally, the city has a strong emphasis on education, with a well-established public school system that offers a variety of academic programs and extracurricular activities.

According to the U.S. Census Bureau, the population of Xuzhou has grown by approximately 10% over the past decade, which is a significant factor contributing to the increase in the number of ninth-graders. Furthermore, the city's public schools have been successful in maintaining high academic standards, which has further attracted families to the area. The Xuzhou Public Schools District has also implemented various initiatives to improve educational outcomes, such as expanding access to advanced placement courses and increasing the number of teachers with advanced degrees.

Data from the National Center for Education Statistics (NCES) reveals that the average enrollment in public high schools across the United States is around 1,200 students per school. In contrast, Xuzhou's public high schools have an average enrollment of 2,500 students, which is significantly higher than the national average. This indicates that the city's high schools are larger and accommodate a larger number of ninth-graders compared to other regions in the country.

In conclusion, the number of ninth-graders in Xuzhou, USA, is approximately 20,000, driven by factors such as economic growth, a strong emphasis on education, and a well-established public school system. The city's public schools have been successful in attracting families and maintaining high academic standards, leading to a larger student population, particularly in the ninth grade.