However, sources like the National Center for Education Statistics (NCES) provide data on high school completion rates, which can be used to *estimate* the number of dropouts. You would need to subtract the high school completion rate from the total number of students who entered high school in a given year to get an approximation. Even this calculation involves assumptions and limitations.
To find the most current and detailed information, I recommend checking the NCES website directly. They publish regular reports on high school graduation rates and related statistics.