MEXICO CITY (AP) — Regulators in Mexico announced fines totaling about $60 million against most of the country’s largest passenger bus lines Tuesday, saying they colluded among themselves for 20 years to keep fares artificially high.

The country’s anti-monopoly commission said the price-fixing may have cost passengers about $170 million in excess ticket costs.

The Federal Commission on Economic Competition said the fines were levied against 18 bus companies and 31 individuals associated with them.

The commission said that between 2000 and 2020, the companies reached six different agreements to charge equally high fares or split routes among themselves, rather than compete among themselves to charge less.