NEW DELHI (AP) — India's central bank says nearly all of the currency removed from circulation in a surprise 2016 attempt to root out illegal hoards of cash came back into the financial system.

The bank says in its annual report that 99.3 percent of the banned currency was returned, indicating that that the government's demonetization program, which caused the economy to stumble and resulted in months of financial chaos, did little to slow the underground economy, which operates on cash.

Prime Minister Narendra Modi announced in a November 2016 television address that all 500- and 1,000-rupee notes, then worth about $7.50 and $15, would be withdrawn immediately from circulation. The banned notes could be deposited into bank accounts but the government said it would investigate deposits over 250,000 rupees, or about $3,700.