Over the years I’ve been inadvertently building a big collection of “graphs that need periodic updating, which makes them more complicated.”

This one depicts coca cultivation in Colombia, and efforts to eradicate it, since 1994. There are two measures of coca cultivation, from the United States and the UN. Eradication has mostly occurred through aerial spraying of herbicides (which stopped in 2015) and through manual uprooting or spraying of plants.

New U.S. data came out yesterday, with a stern scolding from the White House. The UN hasn’t issued its 2017 estimate yet, but local media have reported 180,000 hectares last year.

This chart tells quite a story if you stare at it long enough. But my main takeaways are:

• Aerial herbicide fumigation—the cruelest of the strategies because it anonymously dumps herbicides over small farmers’ legal crops and homes while leaving behind no government presence—is able to reduce coca cultivation from “insanely high” to “moderately high” levels, after which growers adjust and bring cultivation back up to “high” levels.
• Manual eradication seems to correlate more strongly with reductions in coca growing, and it requires at least some on-the-ground government presence. But it’s dangerous for the eradicators, generates conflict with communities, and growers replant if the government disappears once the eradicators vacate the area.
• What hasn’t been tried is actually having a functioning government presence on the ground providing public goods (security, roads, land titles) necessary for a legal economy to exist. The FARC peace accord offers one version of a blueprint for how to make that work, and has improved security conditions, for now. But with the accord’s critics waiting to take power on Colombia’s August 7 inauguration day, that blueprint’s future is in doubt.