When Education Week and National Public Radio examined high school graduation rates across the nation, Idaho’s numbers were conspicuously absent.

The reason: The reports were based on 2012-13 graduation figures, and the feds’ new method of calculating grad rates. Idaho was granted a one-year extension, partly because it was the last state in the nation to roll out a longitudinal data system — the Idaho System for Educational Excellence, or ISEE.

So, here’s what we do know from the numbers that came out this week:

What’s the national graduation rate? 81 percent, in 2012-13. Iowa topped the nation with a 90 percent rate (here, from NPR, is a detailed look at how Iowa did it.) Oregon lagged last in the nation, at 69 percent. (Here, from Education Week, is an interactive map that allows you to look at how states compared, and dig into results by demographics. Again, don’t look for any Idaho numbers, because they aren’t there.)

What’s the best guess of where Idaho stacks up? Well, the state’s 2013-14 rate was 77.3 percent.

Wait, what? Idaho has 2013-14 numbers but it doesn’t have 2012-13 numbers? That’s one way of looking at it. The 2013-14 numbers reflect Idaho’s first round of reporting under the new federal guidelines. And it is a significantly different way of crunching the numbers, so the 2013-14 numbers aren’t really comparable to figures from 2012-13 or prior years.

What’s new with this approach? The big difference is that the states now calculate graduation numbers based on a four-year time window. In other words, Idaho used the students who entered ninth-grade in 2011 as the population to calculate the 2014 graduation rate. Since 77.3 percent of the ninth graders graduated high school by 2014, that’s where the state gets its graduation rate. (The rate counts only students who received a traditional high school diploma in 2014, not a GED or a special education diploma.)