As of the latest available data, there are approximately 45,000 high school students in Grade 12 in Zaozhuang City. This figure is derived from the annual enrollment statistics provided by the Zaozhuang City Education Bureau. The city's educational system has been growing steadily over the past decade, with a corresponding increase in the number of students graduating from high school each year. The rising population and the city's commitment to education have contributed to this trend.

The data from the Zaozhuang City Education Bureau indicates that the number of high school students in Grade 12 has been on the rise, with a consistent annual growth rate of about 3%. This growth is attributed to several factors. Firstly, Zaozhuang City has experienced significant economic development, which has led to an increase in the city's population. As more families move to the city for employment opportunities, the demand for educational services, including high school education, has also increased.

Secondly, the city government has been actively investing in its educational infrastructure, including the construction of new schools and the expansion of existing ones. This has resulted in a larger number of high school students being accommodated each year. Additionally, the government has implemented policies to encourage higher education, which has further increased the number of students pursuing their high school education.

Furthermore, the city's educational system has been recognized for its quality, attracting students from surrounding areas. This has led to a higher demand for high school education in Zaozhuang City, as students from other districts seek to attend the city's reputable schools. The presence of these schools has also contributed to the city's reputation as an educational hub, drawing more families to the area.

In conclusion, the approximate number of high school students in Grade 12 in Zaozhuang City is 45,000, a figure that reflects the city's growing population, economic development, and commitment to education. The steady increase in the number of students is a testament to the city's success in providing quality education and attracting families seeking better opportunities for their children.