Most people guess 20 percent, and for good reason: We've been trained to think that way. The 80-20 rule, also known as Pareto's principle (after Vilfredo Pareto, an Italian economist who devised the concept in 1906), is all around us. Only 20 percent of major studio films will be hits. Same for TV shows, games, and mass-market books - 20 percent all. The odds are even worse for major-label CDs, where fewer than 10 percent are profitable, according to the Recording Industry Association of America.

But the right answer, says Vann-Adibé, is 99 percent. There is demand for nearly every one of those top 10,000 tracks. He sees it in his own jukebox statistics; each month, thousands of people put in their dollars for songs that no traditional jukebox anywhere has ever carried.

People get Vann-Adibé's question wrong because the answer is counterintuitive in two ways. The first is we forget that the 20 percent rule in the entertainment industry is about hits, not sales of any sort. We're stuck in a hit-driven mindset - we think that if something isn't a hit, it won't make money and so won't return the cost of its production. We assume, in other words, that only hits deserve to exist. But Vann-Adibé, like executives at iTunes, Amazon, and Netflix, has discovered that the "misses" usually make money, too. And because there are so many more of them, that money can add up quickly to a huge new market.

With no shelf space to pay for and, in the case of purely digital services like iTunes, no manufacturing costs and hardly any distribution fees, a miss sold is just another sale, with the same margins as a hit. A hit and a miss are on equal economic footing, both just entries in a database called up on demand, both equally worthy of being carried. Suddenly, popularity no longer has a monopoly on profitability.