Almost 145 million passengers used Athens metro lines 2 and 3 last year, which was some 36 million fewer than in 2014, according to figures published on Monday by the Athens Urban Transport Organization (OASA).
The figures mean that an average of more than 450,000 passengers used the underground system each day in 2015, which is the lowest since 2010.
Syntagma was the busiest station, with 9.6 percent of total passengers punching their tickets there.
It was followed by Monastiraki (5.3 percent), Ambelokipi (4.9 percent), Evangelismos (4.4 percent), Megaro Mousikis (4.1 percent), Panepistimio (4.1 percent) and Omonia (3.8 percent).
The least popular stations were Elaionas, Argyroupoli, Peristeri and Aghia Paraskevi.