With the caveat to your caveat that "sales" in the US tends to include anything above 1 or 2 doses. I'm no bartender, but I'll still buy beer by the twelve pack.
Assuming you even get to a jury trial. For most pseudo-distribution cases like this, the defendant is going to plead out, because they know they're dead to rights on the possession charge, and if the judge throws the book at them for that then they may well have been better off taking the distribution plea deal.
If you're caught in possession of a couple grams of coke, then the prosecutor is going to want to get you on distribution. They can say something like "You will be found guilty of possession, we both know that. If you plead guilty on both counts, we can recommend concurrent sentencing and you'll be out of prison in less than two years. If you don't take the deal, we're going to push for everything we can get: even if you get off on the distribution charge, you'll still be in prison for 3 years for possession."
Now, you or I, affluent tech-bros that this forum attracts, know that this is a terrible deal. We'd hire a lawyer, fight it tooth and nail, and walk away with a possession conviction and a slap on the wrist sentence. But if you're some broke kid, with a public defender who's really just there to counsel you on what plea deal you should take, it might not seem like such a bad idea.
Like I said, getting aggregate statistics on how pleading down impacts the composition of the prison population is very hard, but the fact of the matter is most people who end up in prison don’t do so because of anything which looks like only recreational drug use.
https://www.justcriminallaw.com/drug-charges/2023/04/24/drug...
> You can be charged with drug trafficking even if you have not actually sold any drugs. Prosecutors will try to show that you were in possession of a controlled substance and planned to sell or distribute it, even if you were going to distribute it for free or use it with friends.
Texas is finally calming down on weed but back when I was in college I knew plenty of friends that were slapped with "trafficking" because they had some normal amount of grams on them and the cops just went for it. That lets prosecutors scare them into shitty deals because with trafficking you're looking at years of prison.
Considering the scale of the American prison industrial complex, I'm sure plenty of people didn't have good enough lawyers to get the bogus trafficking charges thrown out.
As per OkayPhysicist's point about what counts as possession and trafficking, many drugs require larger dosages with habitual use and the courts do not take this into account.
on edit: I see Komali did a better job pointing out that lots of traffiking and sales are actually possession.
These also vary state to state, and while a white kid with a 1/4 might not get possession, a black kid with the same amount might get the book thrown at him depending on who’s prosecuting the crime.
With the caveat that drug offenses include manufacturing, trafficking, and sales:
Your data is consistent with my claim: I meant the denominator being the prison population, not the entire population. Sweden has about 8600 people in prison so about 37% of their prison population is in there for "drug offenses", whereas in the United States it's less than 1 in 5 per your Prison Policy citation. Obviously if you treat entire population as the denominator, then any comparison of Swedish and American prisons is useless because we incarcerate a much larger percent of the population.
Edit: I realize my original comment said "people" not "proportion of people", but in my defense interpreting it to be people literally is a bit absurd. Sweden's population is about 30x smaller than the United States, so there's no way the counts are comparable!
Edit 2: Actually no I did say “As a percentage”. Whew.
Next, you can see from this sample of federal prison (table on page 2): though drug offenses were the most serious charge for half of prisoners, only 0.1% was for possession. The rest was for trafficking and sales. https://bjs.ojp.gov/content/pub/pdf/dofp12.pdf
This data is from 2010, and the United States has undergone a decriminalization revolution since regarding possession, so new prosecutions are even less likely to be possession claims.