Special education placements (and puzzle)

In the chart above, it's clear that Kentucky "mainstreams" students with disabilities more often than the rest of the country. More of our children are in regular classrooms more than 80% of the time. Fewer are there for shorter periods, and fewer are assigned to fully separate classrooms and facilities.

Students with disabilities are entitled to be educated with other children "to the maximum extent appropriate." The puzzle here is why Kentucky decisions on placement are clearly different from what's common elsewhere.

Are other states keeping students out of regular classrooms who could succeed there? Are they refusing to mainstream when doing so is appropriate?

Or is Kentucky is assigning students to regular classrooms that cannot meet their needs? For example, are we avoiding the added costs that might come with other placements, even when that's what would be right for the students in question?

Notes: the graphed data comes from the "Review of Special Education in Kentucky" released by the Office of Education Accountability in December, available here, with hat tip to Melanie Tyner-Wilson.