Over the weekend, the Guardian reported that Britain had gone kale-crazy, with sales of the bitter brassica surging after its endorsement by celebrities such as Gwyneth Paltrow. The United States could have told them that, having already weathered kale-mania in 2012 and 2013, which featured the "all-kale diet," National Kale Day, Bon Appetit's dish of the year being awarded to a kale salad, kale at the White House Thanksgiving and all the trend stories you could eat.

And verily, there's a reason you're noticing it more often in supermarkets.

"We are definitely seeing a spike in kale," a Safeway spokesman said in a statement e-mailed from his produce team. "It is considered a superfood. We have many new SKU's and different varieties. We are highlighting it by moving it towards the front of our departments so our customers see it immediately.  We will be running a special promotion on it weeks 1-4 at 2 bunches for $3 and expanding display size. It is a rapidly growing commodity."

But what do the data say about how much kale is actually around? The U.S. Department of Agriculture started tracking the production of kale in 1997, and the closest proxy for consumption we have is something called "disappearance": imports plus production minus exports. By that metric, divided by population, we arrive at the amount of kale the United States absorbed per capita:

It looks as though while kale is certainly on the rise again, it's coming up from a crash after 2000; the United States actually used to consume a bit more of it. Compared to the growth in romaine consumption, it barely registers:

But what do those numbers look like in comparison to other veggies? While it's difficult to compare by weight, since leafy greens are lighter than, say, root vegetables, the growth trajectories have differed markedly over time:

Carrots have taken a big hit over the past decade and a half, but the figures for asparagus, broccoli, sweet potatoes and mushrooms have been steadily rising. In comparison, kale is negligible, way down along the bottom of the graph -- which you wouldn't know for all the attention it's gotten in recent years.