US NCES's Condition of Education reported child count data

How many US students are receiving special education services, under what categories of disabilities, and what are their ethnicities?

The US National Center for Educational Statistics (NCES) published data about the numbers of students receeiving special education in US public schools for the year 2019-2020. The publication also provided some high-level descriptions of the students (e.g., the categories of disability, ethnic backgrounds, primary physical location of service delivery, etc.).

In 2019–20, the number of students ages 3–21 who received special education services under the Individuals with Disabilities Education Act (IDEA) was 7.3 million, or 14 percent of all public school students. Among students receiving special education services, the most common category of disability (33 percent) was specific learning disabilities.

Here is a copy of Figure 1 from the report. It shows the categories of disability that allow students to be eligible for special education.

Interested readers can read the entire report at https://nces.ed.gov/programs/coe/indicator/cgg

For those who are keeping score, the percentage of students identified as having learning disability has declined over the years. It used to be the case that about half of individuals receiving special education in the US were identified as having LD. Why has that decline occurred?