With more people holding university degrees, non-graduates are getting rarer in the education service.

Only around 13 per cent of the 34,392 educators in 2016 - the latest year for which figures are available - did not hold degrees.

And out of 372 principals in the same year, only four were not university graduates. These four principals are all currently at the helm of primary schools.

This is a stark contrast from the past, when 147 out of 374 principals were non-graduates in 2000.

Five years later, the number of non-graduates who were principals dipped to 70 out of 365.

With degree holders the norm now, the premium on degrees is vanishing and the wheel seems to be changing direction again.

In recent years, there has been a wider movement across the Public Service to recognise skills and improve career prospects of those who do not hold degrees. In the Ministry of Education's (MOE) case, since 2015, it has had a single salary structure so non-graduate education officers who perform well can progress at the same levels as their graduate peers.

In response to queries, an MOE spokesman said that factors for promotion include a person's track record in performance, his or her potential to take on higher responsibilities and work experience.

"While having a degree in a relevant subject can help education officers deepen their content knowledge for certain areas of specialisation, this is not a prerequisite for career or salary progression," he said.

The spokesman added that MOE assesses educators "holistically" for principal appointments, based on how ready and suitable they are for the higher role. It looks at their leadership and management abilities, their values and how committed they are to developing students.

He said that all teachers - regardless of qualifications - have the opportunity to constantly develop themselves as professionals. They can attend courses offered by the Academy of Singapore Teachers and the National Institute of Education.