THE MBTA’S OPERATING subsidy per passenger seemed to increase last year compared to the year before, but officials say the primary difference was in how the figures were calculated.

In 2015, the T said the subsidy per passenger on the Red, Orange, and Blue lines was 61 cents. That compared to $1.39 per passenger on the Green Line and Mattapan trolley, $1.57 on ferries, $2.86 on bus, $5.75 on commuter rail, and $45.53 per customer on The RIDE, the agency’s paratransit service.

Figures released in late 2016 indicated the subsidy per rider was higher for the heavy rail Red, Orange, and Blue lines (77 cents), Green Line ($1.73), ferries ($3.14), and commuter rail ($6.56), but lower for passengers on buses ($2.77) and the RIDE ($44.53).

Laurel Paget-Seekins, director of strategic initiatives at the T, said the 2015 numbers included nonfare revenues, such as advertising and real estate income, along with fare revenues in the calculation. The 2016 numbers included just fare revenues. It’s unclear why ferry costs went up so much in 2016, and why bus costs went down.

Paget-Seekins said calculating the subsidy per mode isn’t easy. “If someone transfers from Green to Red, how should we allocate their fare? Should administrative costs be allocated by ridership or some other metric?” she asked. She also said looking at just operating expenses skews the results since some modes require heavier capital investments.

“Our heavy rail subsidy looks the lowest, but that’s without considering the capital costs and the other modes as feeders,” she said.