After years of gains, the city's high school graduation rate flatlined last year.

Data released by the state Monday show 60.9 percent of students in the city graduate in four years, a slight decrease over the 2010 rate of 61 percent.

However, the city is reporting a higher rate of 65.5 percent, because it is counting students who received diplomas last August after fulfilling necessary credits.

Statewide, the overall rate jumped from 73.4 percent to 74 percent.

Within minutes of the state announcement on Monday, the city was working to spin it. The city's graphs and charts showcase long-term gains and the press release trumpets more students than ever graduating, but that is because there are more students.

"The numbers are going to go up and down slightly but look at the whole trend. We're talking about one year. Over ten years they keep going up," said Mayor Michael Bloomberg. "And take a look at the graduation rates [from] before we took office. For a decade and a half, it was flat, and then they [rise] this way. So if they go this way, slightly more or less... you know, come on."

The mayor and Schools Chancellor Dennis Walcott focused on the bright spots in the new numbers.

"Lines are going to go up and down a tiny bit, but overall the trend is positive," said Bloomberg.

State data also shows more black and Hispanic students are finishing high school, but an achievement gap remains between white students and minorities.

In a statement, the teacher's union says the report is a sign that the mayor's education reforms are not working.

These are very significant numbers for the mayor, released one day before the 10th anniversary of his taking control of city schools. He has used graduation rate gains as proof his education reforms are working, especially since 2010, when the state acknowledged test score gains by elementary and middle schools may have been the result of easier tests.

Now Bloomberg in pointing to other numbers, like enrollment.

"If we weren't doing a good job, are you as a parent going to send your kid to our schools? No. The fact that we have more students Is something that we should be really proud of," said the mayor.

For years there have been two types of diplomas, the Regents and the easier Local. The percent of city graduates relying on the easier diploma has decreased from 12 percent in 2010 to 8 percent in 2011. But the State will no longer issue the Local diploma.

Bloomberg said he supports raising the bar but next year's numbers may be even worse.