Rat sightings are down 80 to 90 percent in New York, thanks to a “rat reservoir” strategy expanded by the Mayor’s office last year, the city’s Health Department announced.

Mayor Bill de Blasio invested $2.9 million to expand the tool in fiscal year 2015, a statement from the department reads. That additional funding allowed the program to expand its staff from nine to 50 people.

The program involves “rat indexing” areas of Manhattan and the Bronx to identify high concentrations of rats, which are then heavily baited. Those areas tend to develop around parks, subways and sewers, officials said.

The report also notes that Manhattan saw a 30 percent drop in rat control failure rates between 2010 and 2014, DNAInfo notes. Every tracked district in The Bronx also saw decreased failure rates within the same period, according to the report.

Lower Manhattan Councilwoman Margaret Chin expressed some optimism for the findings, according to DNAInfo.

"We cannot be complacent in our efforts to protect public health,” said Chin in a statement. "Even though our City’s rodent problem has been around for centuries, and is likely to continue for centuries more."