BOGOTA, Colombia -- The annual United Nations survey on coca plant production in the Andean region serves as a kind of drug war report card -- yet it's hard to tell whether Colombia is passing or failing.
Using satellite imagery, the UN estimates the amount of land planted with coca bushes that grow the leaves used to make cocaine. But even though the latest figures show Colombia's coca acreage declining to its lowest point in years, no one is celebrating.
That's partly because coca farmers in Peru and Bolivia have made up much of the slack.
In addition, Colombian guerrillas and criminal gangs that earn huge sums from the drug trade are expanding into lucrative new ventures, such as growing hydroponic marijuana and setting up illegal gold mining operations.
"Despite effective government anti-drug actions, the criminals have gradually acquired new sources of financing," said a recent editorial in El Tiempo, Colombia's largest newspaper.
On Sunday, El Tiempo published the latest UN coca survey that was leaked to the newspaper ahead of its official release next month.
It showed that in 2012, peasant farmers in Colombia grew 118,000 acres of coca. That's a huge reduction from the peak year of 2000, when farmers cultivated 402,000 acres. In fact, it was the lowest figure in nearly two decades.
Measuring drug crops, however, has always been an imperfect science. Cloud cover can mar satellite imagery and obscure the results. It's also difficult to estimate how much cocaine can be produced from an acre of coca because farmers have switched to strains with higher alkaloid contents while some of their drug fields are denser than others.
One Colombian anti-drug expert claimed that the country's anti-drug police, who carry out aerial fumigation and manual eradication of coca fields, do much of their work at the end of the year shortly before coca acreage is measured. This practice produces a better result on the UN survey. But during much of the year, he said, actual coca acreage is far higher and farmers are able to harvest their fields several times before the crop dusters arrive.
"There is a perverse incentive to wait until the end of the year to fumigate," said the expert, who did not want to be quoted by name because he often works as a consultant for the Colombian government.
Still, he and other analysts agree that cocaine output has been substantially reduced. In 2001, Colombia's annual cocaine production was estimated at about 700 metric tons, a figure that has since dropped to less than 200 metric tons as coca acreage has fallen. (A metric ton equals slightly more than 1.1 US ton.)
Experts point to a variety of reasons for the reduction.
The ongoing fumigation campaign may have finally convinced some farmers to get out of the drug business. There may also be less demand for coca leaves as Colombian authorities have focused on dismantling downstream targets, such as cocaine laboratories and trafficking organizations, said Daniel Mejia, director of the Research Center on Drugs and Security at the University of the Andes in Bogota.
In some areas of Colombia "lots of farmers are throwing in the towel," said Sanho Tree, director of the Drug Policy Project at the Institute for Policy Studies in Washington. "But in other regions they still think they can game the system."
Coca production in the countryside's more populated areas has dropped sharply but along Colombia's border with Ecuador and Venezuela and near the Pacific coast, where there's minimal government presence, growing coca continues unabated, said Alvaro Balcazar, who has worked with the Colombian government on anti-drug programs in rural areas.
And even though coca acreage is down, that doesn't mean peasant farmers have been sold on the virtues of planting bananas, pineapples and other legal crops. Authorities say plantations of highly potent marijuana are springing up, creating what's been called Colombia's second marijuana bonanza, following the drug's initial boom years in the 1970s.
Encouraged by the high price of gold, other coca growers are transitioning to illegal mining. A recent drop in coca acreage in northwestern Colombia's Antioquia department -- from 11,700 acres to 7,500 acres between 2010 and 2011 -- is largely attributed to a switchover to illegal gold mining.
For farmers, gold mining is easier and more profitable than growing coca because they don't have to invest in pesticides, hire coca pickers at harvest time or worry about government crop dusters. And unlike drug traffickers, illegal gold miners don't face the threat of extradition to the United States.
For Colombian authorities, the problem is that the mines are largely controlled by criminal gangs as well as the Revolutionary Armed Forces of Colombia, or FARC. According to El Tiempo, the FARC -- which long relied on drug trafficking, kidnapping civilians for ransom, and extortion schemes to fund its war -- now earns about 20 percent of its income from illegal gold mining. The government consultant said FARC units now have separate financial managers keeping tabs on profits from both drugs and gold.
The other factor offsetting coca's decline in Colombia is the so-called balloon effect. When drug producers come under pressure in one country, they often shift operations to nations where law enforcement is less intense -- similar to the way that when a balloon is squeezed on one side, the air bulges out on another side.
For example, Peru and Bolivia were the top coca producers in the early 1990s and sent unrefined coca paste to Colombian labs where it was transformed into cocaine. Amid a crackdown on aircraft ferrying coca paste to those labs, most production relocated to Colombia, leading to a spike in acreage at the start of the 2000s.
Now, the plantations are returning to Peru and Bolivia. Although the 2012 UN figures on Peru have not yet been released, Peru emerged in 2011 as the top coca producer in the region, topping Colombia for the first time in more than 15 years.
"The problem shifts back and forth between countries," Mejia said. "We are in the same place that we were 15 or 20 years ago."
As a result, frustrated Latin American leaders are increasingly insisting that illegal drugs be treated more as a public health issue than a law enforcement priority. Much is at stake. The drug war is costing their countries billions of dollars annually and thousands of lives. And they don't seem to be getting anywhere.
Or, in the words of Colombian President Juan Manuel Santos, one of the main advocates for reform: "Sometimes we all feel that we have been pedaling on a stationary bicycle. We look out to the right and left, and we still see the same landscape."