Nearly 60 percent of Florida school districts, including Broward County Public Schools, saw their state-issued grade tumble Friday.

Broward’s fell from an A to B, a grade the nation’s sixth-largest school district last earned in 2007.

Miami-Dade County Public Schools maintained a B, its average since 2008.

The Florida Department of Education released report cards for all school districts Friday, two days after it issued letter grades for elementary and middle schools.

The weaker district report cards were not a surprise, since the school letter-grades slid under pressure from tougher scoring on the state’s standardized exam, the Florida Comprehensive Assessment Test, or FCAT, as well as a more complicated formula to compute school grades.

For example, Broward had 20 percent fewer A schools, or 41 fewer.

Miami-Dade managed to lose only 11 percent of its A-ranked schools.

Statewide, the number of D-ranked school districts grew to 7 from 1 in 2011. No district flunked.

Broward Superintendent Robert Runcie said earlier this week that the drop in performance was expected because of the tougher standards.

“We fared relatively well compared to what was expected across the state in the adjustment downward in performance,” he said.

At the same time, the release of the district grades and the report cards for middle and elementary schools have not quelled growing discontent with Florida’s system to test students, rank schools and evaluate teachers, who will see test scores drive half their professional evaluation.

Said Runcie: “While we do need to have an accountability system, I firmly believe in that, we can’t let that accountability system define our instruction and how teachers are working in the classroom.”

Miami-Dade schools chief Alberto Carvalho said that traditionally the district has traditionally seen students improve their performance year over year when the same scale is used. The district saw students improve again this year.

“Our teachers, our students and our community have much to be proud of. In the face of both a more difficult FCAT and higher cut scores, our district managed to hold its own and actually do better than many of Florida’s large school districts,” Carvalho said in an email.