The Rotorua Daily Post asked the Ministry of Health for the number but was told it was "not captured in the ministry's method of data collection".
Ms Wilkie believed more DHB involvement in placing trainees could help fill hard-to-staff areas. "If the trainees don't get exposure to hospitals in provincial areas, as part of their training, they are less likely to accept a position there when they qualify as a consultant."
Senior psychiatry roles and senior roles at Taupo Hospital's emergency department were also difficult to staff, Ms Wilkie said.
Nationwide, 2303 graduates have completed the three-year minimum requirement of the scheme since 2009.
The Labour Party's health spokeswoman Annette King supported the scheme, but believed it should cover more shortage areas.
"It's another important tool to encourage graduates into areas that aren't popular.
"What I think needs to happen now is to look at other shortage areas and the numbers being trained to support them.
"For example, there's a real shortage of dental therapists and there's a growing shortage of oncologists.
"Those areas could also benefit from voluntary bonding, particularly in terms of getting people to go to regions where there's some real shortages of professional skills."
A formal review of the scheme will be conducted in 2016 to update the ministry's "knowledge and understanding of the impact of the scheme ".