So how much stuff are you still missing?

This is what my collection look like:

Arena 7/200, 4% (Whatever the 200 arena only cards are, I only have the ones from new player experience)

Dominaria 635/1040 (61%)

Guild of Ravnica 868/1076 (81%)

Ixalan 193/1076 (18%)

M19 Gift Pack 0/0 (0%)

Magic 2019 475/1176 (40%)

Mythic Edition 4/12 (33%)

Rivals of Ixalan 171/800 (21%)

Complete collection 2353/5396 (44%)

Singles 868/1349 (64%)

You need one of the varied MTG Arena helper tools to get this info.

I think analizing only rares and mythics makes the data more readable, even if it cuts off some information

I have 76% unique and 64% total. But i agree that rares and mythics are more important as data, since i have 100% commons and uncommons in GRN, DOM, M19. Missing almost all XLN and RIX sets.

Btw, why do you have 5396 cards as complete collection? I use pro tracker and it counts 5324 cards.

My collection is as such: https://mtgarena.pro/progress/#WrightJustice

My data is from the MTG Arena tool. Pro-tracker is probably not counting the cards you can't actually unlock like arena-only cards or mythic edition or something like that...

Pro tracker's collection page is rather confusing to be honest.
Edit: Plus I just checked and it shows my last booster open from 11/20/2018. I've done some since so I don't know how good this tracker is actually working. The collection page shows every single card and no generalization of collection progress. Maybe I should look under Progress.

I guess Pro Tracker isn't the best in figuring out your collection progression.
Tis confusion.
I'm not liking this thing. That isn't my gold and gems balance and the booster last shown is from late last month. I don't think this is working ok. I fire it up before I fire up the game so I don't understand why it's not tracking properly. I think I'll email the developer.

Just looked and I'm running the latest version that happened to come out 11/21/2018... right when my information is frozen. Can't seem to be able to communicate with the developer unless I join some other sites which I am not going to do.
Sigh

Data from MTGArena as well:

Arena: 4% New Player Experience and that's it.
DOM: 78%; 50% Rares, 49% Mythics.
GRN: 89%; 69% Rares, 63% Mythics
IXL: 22%; 21% Rares, 24% Mythics. ICR and Crafting does that for you.
M19 Gift Pack: 0%. Duh.
M19: 78%; 56% Rares, 31% Mythics. May want to craft some Bolas.
Mythic Edition: 3/12. Teferi, Vraska, Ral; one each.
RIX: 27%; 16% Rares, 32% Mythics. Mostly ICR and maybe starter decks; I don't think I have crafted a single RIX mythic.
Overall: 58%; 41% Rares, 38% Mythics.
Current WCs: 13 Common, 31 Uncommon, 3 Rare, 2 Mythic.