The IIF said the estimates, which include unrecorded flows captured by net errors and omissions, are based on official reserve data and mark a 22nd straight month of outflows from China.

The Washington, D.C.-based global finance industry group said that China’s official reserve intervention in January was smaller than the $102 billion estimated for December. But it cautioned that the estimates were only approximations and could change significantly once full balance-of-payments data is released, typically three months after the end of each quarter.

The IIF, incorporating recently released partial State Administration of Foreign Exchange (SAFE) data for the fourth quarter, said it now estimates that China’s 2015 net capital outflows totaled $463 billion, or $637 billion including errors and omissions.

The slowing of China’s growth and manufacturing sector during the past year has hit investor sentiment towards the world’s second-largest economy, causing volatility in its capital flows, putting pressure on its yuan currency and forcing the central bank to intervene in currency markets. The IIF said a reversal of non-resident capital inflows prompted largely by repayment of dollar debt by Chinese companies also had combined with increased capital outflows from residents.

Last week however, SAFE said that China’s foreign exchange reserves remained abundant and risks from cross-border capital movements were under control. It said China’s foreign exchange reserves fell $512.66 billion in 2015—the biggest annual drop on record—to $3.33 trillion, while China had short-term foreign debt of $1.02 trillion at the end of September.

The SAFE said that of the 2015 drop in foreign exchange reserves, $342.3 billion was due to trade and investment transactions while $170.3 billion was caused by currency and asset price changes.