Slightly more Kiwi graduates are staying in the country, despite falling pay rates.

Latest Ministry of Education statistics show that 9 per cent of domestic graduates left the country within a year of earning bachelor's degrees in 2014-15, down marginally from 10 per cent in 2011-12.

There have been similar reductions of 1 to 2 per cent in the past year in the proportions overseas in each of the first nine years after graduating - reflecting New Zealand's buoyant job market, particularly compared with Australia.

Yet median earnings for many graduates with diplomas, degrees and higher qualifications dropped in real terms, despite an increase in overall national median earnings.

Consequently the advantage of having a bachelor's degree narrowed slightly from median earnings 40 per cent above the overall national average five years after study in 2013-14 to 39 per cent above the average in the latest year.

The advantages of having higher degrees dropped even more - from 65 per cent above after five years to 59 per cent for an honours degree, from 67 per cent to 60 per cent for a master's, and from 104 per cent to 98 per cent for a doctorate.

Berl economist Kel Sanderson said the changes reflected the strong growth in the construction industry compared to graduate sectors such as government and the professions.

"All the tradies are doing really well and they are probably pushing the median up," he said.

However graduates still earn more than the national median of $38,663. Even in the first year after graduating, median incomes are $39,614 for those with bachelor's degrees, $45,191 for those with master's and $63,567 for doctorates.

Ten years after graduating, medians are $64,553 for bachelors, $76,219 for masters and $88,352 for doctorates.

Medical bachelor's degrees still yield by far the highest incomes with a median of $124,800 after 10 years, followed by bachelors in dentistry ($95,400), banking and finance ($86,700), law ($82,100), veterinary science ($81,100), accountancy ($81,000), engineering ($80,400) and information technology ($79,200).

The latest data shows that 31 per cent of all bachelor's graduates are overseas in every year from seven to 10 years after graduation - exactly the same as in 2011-12, indicating that the increased tendency to stay home among recent graduates has not been matched by any increased tendency to return for those who left some years ago.

Those most likely to be overseas are bachelors in information technology (38 per cent), engineering (37 per cent), architecture (36 per cent), management and commerce (also 36 per cent), and natural and physical sciences (34 per cent).

For bachelors in society and culture, 31 per cent are overseas after 10 years - including 34 per cent of law graduates.

For bachelors in health subjects, 29 per cent are overseas after 10 years. This includes 35 per cent of medical and dental graduates but only 23 per cent of nurses.

Only 30 per cent of bachelors in creative arts, 23 per cent in agriculture and environmental fields and 17 per cent in education, are overseas after 10 years.