"Until 1 April 2007, borrowers who went overseas before their loans were repaid were expected to work towards repayment of the full loan balance within 15 years. Each year, the borrower was required to pay one-fifteenth of the outstanding principal and all the interest accruing on the loan. Many borrowers – especially those with larger loans and those who had low earnings while overseas – found repayments very difficult and many ended up in arrears."
Section 3.1 http://www.educationcounts.govt.nz/__data/assets/pdf_file/0003/17238/Chapter-3-Student-Loan-Scheme-Annual-Report-2007.pdf
So, 1/15th of a $70k balance is $4667 + the interest that was due on the principle that year, which for FY1999/2000 which was 7.0% (http://www.beehive.govt.nz/node/6880) which gives you an amount of $4900, or a total of $9567.
