Phish.net lists 871 songs written and/or played by Phish, but that includes 22 that were "only" teased or jammed, 42 unperformed originals, and 533 covers, of which 289 weren't played beyond their debut. Of the 274 originals left, 42 were only played once and most were written decades ago.

But don't discount the band's originality yet, as there's good evidence of two forms of overlooked balance. You can see them both in today's chart (the next in a series), which involves several variations on a population pyramid (a.k.a an age-sex graph, a variation on a paired-bar graph).

This chart treats Phish's repertoire of songs as a population, disaggregates them by age (measured by year of debut, with the oldest on top), and distinguishes originals from covers (rather than male/female, as is typical). Further,

the bars for each age are segmented ("stacked") to differentiate songs that were only performed once (the lighter tips of each bar) from those performed more than once (the darker root of each bar). Finally, to help understand growth in the repertoire, rows are labelled with studio album releases and musical costume albums performed in the given year.

Halloween performances, as well as the cover-rich summer of '98, help explain growth in the repertoire, often with songs never performed again. But they also belie a relative balance in material: The number of originals and covers played more than once is nearly the same, at 232 and 244, respectively.

And, yes, the band's introduction of new original material has slowed since their prolific early years. But setting aside years when Phish didn't perform any public shows, the slowdown isn't as dramatic as you might have expected. The number of debuts in four recent years is only a minor reduction from the '90s, during which (Halloweens aside) new material was already slowing down from the '80s - but so, gradually, did the number of shows. And the reduction in shows over the last 20 years both partly explains the lower rate of debuts and, as a control variable, reduces its difference.

When they do play, surprises continue - and, arguably, at a comparable rate. But the biggest factor in repertoire expansion has of course been time off, including the "hiatus" and "breakup". With no fall tour, it'll take another debut-rich summer for 2015 to compare even to recent years.

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