North’s Carolina’s annual school performance data released Wednesday was mostly bad news for the Rowan-Salisbury School System.

The data — for the 2014-2015 school year — shows four schools in the Rowan-Salisbury School System received a grade of F, and 15 schools received a grade of D, according to Wednesday’s data.

The results reflect a small but significant increase in the number of schools considered underperforming. In, the 2013-2014 school year, 14 local schools received a grade of D and one school received a grade of F.

Only one school — Rowan County Early College — received a grade of B, according to the 2014-2015 rankings. Last year, Carson High, East Rowan High and Bostian Elementary also received a grade of B.

No local schools received an A.

In response to the grades, Rowan-Salisbury Schools Superintendent Dr. Lynn Moody said it’s disappointing to see a decline when students and staff worked so hard.

“At the same time, with the many changes that were introduced and implemented last school year, we knew it was a possibility,” Moody said. “While this news is disappointing, it is not discouraging. Transformation is not just a one-year journey or an event — it is a process.”

Examples of changes include a three-year strategic plan and the system’s one-to-one technology program.

Schools receiving a grade of F this year include:

• Koontz Elementary

• Knollwood Elementary

• Knox Middle

• North Rowan Elementary

Schools receiving a grade of D include:

• Erwin Middle

• Overton Elmentary

• China Grove Elementary

• Corriher Lipe Middle

• Isenberg Elementary

• Hurley Elementary

• Landis Elmentary

• North Rowan High

• North Rowan Middle

Below: Performance data results from the four worst performing Rowan-Salisbury Schools, according to data released Wednesday. Red is 2013-2014 score. Blue is 2014-2015 score.