From an article on the New Mexico school system
The [education] department evaluated the schools in a number of areas, including academic growth, attendance rates and graduation rates, then graded them on a curve.
In other words, while a total of 100 points was possible, the department gave “As” to the top 10 percent of schools in the state.
“Our bar is the top 10 percent,” Skandera said. “That’s how we’re measuring success. I think that’s an excellent starting point for asking, ‘How are we doing?’ And let’s benchmark against that and go forward and aspire that every single one of our schools is in the top 10 percent [emphasis mine].”