Everybody's heard about the economic growth of China, India, Mexico and Russia (well, at least, until recently). But it turns out that success has come with a big asterisk: These countries now are the biggest source of illegal money in the world, exporting $1 trillion a year in laundered funds, drugs, and under-the-table payments.

This is the dark side of the developing world, according to a new report by international corruption watchdog Global Financial Integrity (GFI). And it's growing -- by 10 percent a year.

China leads the pack, contributing just under $250 billion in illicit financial flows in 2012, the latest date for which data is available. Russia was nearly $125 billion. India, the third most corrupt developing country by this measure, contributed just shy of $100 billion to the world's growing pool of illicit money.

All told, the top 10 countries account for a 'staggering 67 percent of the global total by volume,' the researchers note.

The takeaway is that these countries, whatever success they have had, are still struggling to contain corruption and illegal finance that can easily undermine growth and prevent the countries from building on their successes.

In all, some 145 developing countries around the world funneled anywhere an average of between $1 million and $125 billion between 2003 and 2012.

Geographically, the breakdown looks like this (notice all the red in Asia, which is responsible for more than 40 percent of illicit financial flows from developing countries).

Illicit financial flows are particularly problematic in developing countries, where financial systems are often more vulnerable to corruption. The trillions of dollars represents money that would otherwise flow through economies and help spur growth. Instead it ends up in the hands of criminals and corrupt officials and businessmen.

'Illicit inflows often deprive developing countries of significant customs duties, they facilitate crime, and they flow into the underground economy,' the report notes.

Curbing the amount of illegal money flowing in and out of developing countries is a tall task. The most common way in which illicit cash moves unnoticed is through the under or over reporting of trade, a practice that is both illegal and extremely difficult to track.

Like most other forms of money laundering, trade misinvoicing, as the practice is known, is perpetuated by a general opacity in the global financial system. Companies in developing countries are often able to operate without sharing important information about their finances, transactions, or even ownership.

One of the keys to reversing the current trend is shedding a light on this sort of information by calling on developing governments worldwide to hold companies accountable, and thereby creating transparency where there has been little. And why not start with Chinas, Russias, and Indias of the world, where most of the illegal money is coming from.