Similar to how you did yours, it use to be much higher, but I stop downloading as much. 

I have no idea, I have unlimited use, so never occured to me to check, or is this for data plan users only.

See how frugal I am. I have used 14 GB on my phone this month. The phone has unlimited internet for $20 a month and my data speeds are in the 20 to 30 Mb range. All my streaming like Funimation and Netflix are from the phone and I cast to my TV in 1080p .
Now for gaming, I have a stand alone mobile hot spot with 30 GB data cap. On the PS4 so far this month I have used 22 GB for game patches and online play. I do have to be careful with any games I buy to make sure the patch sizes will be doable. World of Tanks is a free download but it's 30 GB and I won't be able to do that much because the mobile hot spot will not allow overages, and just shuts down.
I'm doing fine with this set up. The Witcher III patch download was planned at the start of a cycle so it worked out fine. If I do max out my mobile hot spot I still have unlimited video streaming from the phone.

What in the world am I reading?

You know your phone will almost certainly have an option to turn itself into a mobile hotspot for you right? As in you could use your phones unlimited net from your PS4 and download your games that way at night while you're asleep or so?

If you have android, go into Settings and under Wireless and Networks click on the "more..." option, should bring you to a place which features "Tethering & Portable Hotspot" Just go into the settings now and turn off the power save option on it, fire up the PS4 and connect it to the phones WiFi hotspot instead of your Data Capped stand alone thing.

Edit - Just.. for the love of all that is Holy make sure that you don't have Wi-Fi connecting your Phone to your Stand Alone Mobile Broadband when you do this... or you'll just be using the Data Capped Mobile broadband rather than your unlimited 3/4G network Data.

Aye, you really need it to be 4k so you can see that utter look of regret in their eyes, it's the only thing that works for me too.

Wow, I've never checked my bandwidth usage on any of my Xbox Ones before, but the main one (that I just happen to be near right now) alone (of the four XB1s, in addition to countless other devices and consoles) shows that in the last 10 months, we have never used less than 320 GBs in a month. Our high was in November with 724.66 GB. By my calculation, we have averaged a little over 470 GBs per month over the last ten months on just this one device. Now I want to do some more digging to see what the usage is on some of the others.

206GB last month is what my Fritz Box says. But I didn't download a game last month and some stuff I streamed was in my partner's house so yeah, I think my average is some higher

Average about 160 GB

According to my computer and Xbox for this past month, around 500GBs. Phone data, no idea. Probably not much since I don't use it much though.

I have an Unlimited Plan. But in average we would only spend about 100gb. It should be much lower now since the last 3 months since im mostly at uni. Especially how me and my brother are the ones who mostly use the internet.

For phone I currently have a 1.5 gb plan. I try to use all of it especially if I have leftovers on its last day for its monthly bill.