Here is a quick intro to the problem, but if you're interested only on the question, I think you may skip to the last paragraph.
I have installed Ubuntu Mate on my laptop with the recommended amount of swap, (according this answer and this page and soem other things I read). According to my uses I figured that that should be enough (I have 5GB of ram so I set up 5GB of swap). However, whenever I check my swap space, I notice it is empty. Similarly, it is very hard for me to see my RAM with more than 50% use. This is making me think that I may have oversized my swap space (I don't need hibernation to be always possible btw). For me the only way to be sure is monitoring how much memory/swap I use on a daily basis.
So the question is: how do I monitor the swap/memory use on my system? (So I can open a file at the end of the week and be able to plot my memory and swap usage over the last days.) If that already exists (I haven't yet found anything), how do I access it?
PS.: I would rather avoid writing a script that runs every x seconds on crontab and collect this information.