Publication of the new National Standards data, which show whether children are reaching expected reading, writing and mathematics standards, has renewed debate around the controversial system.
Aggregate results, which provide a national snapshot of last year's achievement levels, show a slight improvement on 2011.
At least 70 per cent of students in Years 1-8 achieved their respective standards in reading (77.4 per cent), writing (70 per cent) and maths (73.6 per cent).
Maori and Pasifika students continue to trail other pupils, despite Pasifika students making the most progress between years.
Male students lagged in reading and writing achievement compared to female pupils.
Results for Hawke's Bay schools are set to be released this month.
The country's largest teaching union, the New Zealand Educational Institute, slammed publication of the results, saying the most recent data failed to contribute anything new.
President Judith Nowotarski said the National Standards were as unreliable and invalid as last year in terms of judging teacher or school effectiveness.
Educators have warned of consistency problems in the reporting of National Standards achievement results since the system's 2010 implementation.
Education Minister Hekia Parata said the data gave a "comprehensive picture of our system and what we need to be focusing on".
But she was unable to guarantee uniformity between schools in their reporting of National Standards results when questioned in Parliament.
The Education Ministry was still working with about 13 schools which had not produced accurate data, she said.
"This is only the second year that the National Standards data has been reported and we expect the quality to continuously improve each year."
The ministry had established an expert advisory group to investigate issues with National Standards data.