The Boston school system rated 93 percent of its teachers as exemplary or proficient under a new evaluation system, although ratings varied fairly significantly from school to school.

Overall, 13.5 percent of the system’s roughly 4,000 teachers received an exemplary rating, 79.5 percent received a proficient rating, 5.8 percent were rated as needs improvement, and 1.2 percent were deemed unsatisfactory. The ratings covered the 2012-13 school year.

At individual schools, the ratings varied considerably. At the flagship Boston Latin School, for example, 18.8 percent of the teachers were rated exemplary, 76.8 percent rated proficient, 4.5 percent needs improvement, and none unsatisfactory. At Condon Elementary in South Boston, 25 percent of the teachers were rated exemplary and 75 percent proficient, with none rated as needing improvement or unsatisfactory.

At Bates Elementary in Roslindale, by contrast, no teachers were rated exemplary, 78.3 percent were rated proficient, 13 percent were rated needs improvement, and 8.7 percent were listed as unsatisfactory.

The new evaluation system replaces an old one that was widely ignored, with less than a quarter of teachers actually being evaluated in 2009. Nearly 40 schools in 2009 did no evaluations at all. The new evaluations cover 93 percent of the system’s teachers and resulted in the removal of 31 teachers “who persistently struggled to meet the needs of our students,” according to a release issued by acting schools superintended John McDonough. The 31 teachers who were removed were not included in the overall ratings because they left before the end of the 2012-13 school year, McDonough said.

McDonough said the ratings raised several concerns. He noted 37 percent of educators working at the system’s central office were rated exemplary, more than twice the level for educators working in schools. He also said the data indicate educators who are male, African-American, and over the age of 50 tend to receive worse rankings than other teachers. Nearly 10 percent of black educators, for example, were rated as needs improvement and 3.2 percent were rated unsatisfactory. The ratings for blacks were twice the overall system’s average.