Earlier this week we asked you to guess the highest-selling singles and albums to come out of Minnesota—and the answers to those two big questions will be revealed this Sunday night on the Current Presents: The Best-Selling Minnesota Artists of All Time.

But before we get down to brass tacks, I wanted to share a few notes from my research. This kind of stuff can get pretty dry, so I'll try to keep it as lively and interesting as possible with the help of some pretty fascinating graphics from the Recording Industry Association of America (RIAA). Everyone likes graphics.

Who tracks album sales?

When I first had the idea to compile a list of best-selling albums and singles from Minnesota artists, I thought, Why hasn't anyone done this already? Surely this will be the easiest information-gathering of all time. And when I think back to that pre-research time now I laugh and laugh at how blissfully naive I was about the music industry and its data.

The truth is, aside from the very trackable sales happening in the modern age through outlets like iTunes, no one actually knows exactly how many copies of a particular album or single have sold. Let me repeat that: NO ONE ACTUALLY KNOWS exactly how many copies of a particular album or single have sold, not even the artists themselves. There are a few reasons for this.

Prior to the RIAA forming in 1952 and beginning their process of certifying gold albums in 1958, only the record companies themselves were keeping track of how many copies of each title had been manufactured and sold. And at that point in time there was really no way of knowing what happened to the albums once they left the manufacturer and were purchased wholesale by the individual record stores—maybe they all sold, maybe some of them ended up in dusty bins underneath the shelves. Also, not to say that record companies aren't run by upstanding and truthful people, but there was nothing preventing the labels from inflating their own sales numbers to make themselves look good. As such, any information available about album sales prior to 1958 is uncertifiable.

Then along came the RIAA, whose original mission was to "administer recording copyright fees and problems, work with trade unions and do research." After a few years on the market the RIAA decided to start rewarding singles and albums that performed especially well. In 1958 they began offering Gold Awards for singles and albums that had reached $1 million in sales, and after a decade and a half they changed the criteria to 500,000 units.

This was good thinking on the RIAA's part—back in the 1950s, a 45rpm vinyl record could range anywhere from 50 cents to a dollar or two each, so it was difficult to compare artists in terms of dollars earned—and by the time we get to the mid-'70s we start to see some awesome, easily trackable data regarding the music industry at large. Which brings us to our first chart!

All data courtesy of the RIAA

On the left we have a pie chart that shows the breakdown of all the different formats of music that were being sold in 1983, and on the right we can see how drastically things had already changed 10 years later. And this is where things start to get interesting.

Before we get too far, another note about tracking sales: In addition to the RIAA, Nielsen SoundScan began providing sales data to record companies and industry insiders in 1991. The two companies gather their data a little differently—the RIAA tracks the number of units shipped from the manufacturers, minus unsold units returned to the manufacturer by record stores, while SoundScan gathers the data directly from the cash registers at stores. Because of this, Nielsen SoundScan's data is much more accurate and precise, but it is also more closely guarded. Nielsen charges a significant fee for researchers who wish to access their database.

Ok, now on to the good stuff.

40 Years of Data

Over the course of researching the best-selling artists to come out of Minnesota, I spent a lot of time digging into the decades of data that have been gathered by the RIAA. Much of that data was specific to individual artists (and will be revealed on Sunday night), but I also found some really intriguing charts and graphs that relate to the format music has been sold in over the years and how overall sales have fluctuated.

Are you ready for another chart? I know I am.

And in the 2000s, things shifted dramatically again:

Because of this, we'll see some surprisingly results pop up when we examine the best-selling singles from Minnesota vs. the best-selling albums. In some years it was easy for a single to sell a million or more copies because that's what people were buying, where in other years it was virtually impossible to purchase a single song and fans were forced to buy the entire album. I'll have more on that and how it relates to Minnesota artists' sales very soon.

But while these individual pie charts are interesting and all, one of the most startling and compelling findings in the RIAA database was a graph that shows the rise and fall of all of the formats of music over the past 40 years. And this is where things get CRAZY.

On the left, the RIAA has tracked the total number of units sold in the U.S. each year, broken down by format, and on the right they have tracked the sales in terms of dollars. You'll notice that the number of units purchased has increased steadily from the time they started collecting the data until now—including a huge leap in sales over the past seven years as people download more and more music online. But on the left, what we see is that while the music sales are currently at a 40-year high, the money brought in from these sales is the lowest its been since 1988.

Here's that chart again, only this time adjusted for inflation:

Suddenly, all of the industry's freaking out and melting down over the internet's impact is starting to make a lot of sense.

Tune in this Sunday night at 10 p.m. for the Current Presents: The Best-Selling Minnesota Artists of All Time, and check back tomorrow for even more nerdy analysis of music industry data as it relates to local musicians.

Previously:

• Who are the best-selling Minnesota musicians of all time? Take a poll to see if you can guess the best-selling songs and albums to come from Minnesota, and we’ll reveal the answers this Sunday night at 10 p.m. on the Current Presents.

• What does it take for a musician to "sell out" in 2014? Artists from Communist Daughter and Dark Dark Dark weigh in on the brave new world of licensing music for use in advertising and film.