I should have phrased the OP better.
It's not linear or constant acceleration.
2010-2015 felt much slower than 2000-2005 despite 9/11, the War on Terror and the Battlestar Galactica reboot. Everything slowed down, and now everything seems to be moving faster.
Time passes more slowly when you have to familiarize yourself with something, or when there are dangerous or painful elements. You might recall that (eg) some boring project you had to do as a child took what seemed to be a small eternity; same with being in a one-hour class at school if you haven't done your homework and fear the teacher may examine you.
However, it also happened that playing when a child may seem to last for a vast time, and this seems to be because your mind is more active and focuses on more things concurrently. I think the best of example of that is when you sleep: one can see incredibly complicated dreams that (in the dream) often last
whole years: the mind is working far faster than at other times.
I actually did self-examine this back in my first couple of university years, ie specifically would examine how my sense of time (while thinking) could be altered so that I could think more in the same amount of time.
The older most people get (and to a degree, all people) the less they tend to think. Primarily because thinking is tied (for a number of reasons) with problem-solving, and most people tend to reach a point where they just accept some stable kind of existence. Afaik this is also argued (in research) to potentially lead to illnesses like Alzheimer's.
Trivia: Actually, when I was 9 years old, I had the theory (among other theories) that the reason why other people seemed off to me was that they were in another time, and that there was a specific flow of time for all: one only seemed alive and "there" when they were on exactly the same part of time as you

Unfortunately this doesn't seem correct; but I once did write a very small story when someone deliberately allowed the years to go by just so that he would force other people to get old too.
No fear, though; I replaced that theory with a "better" one, having to do with a forced caste humanity, overwatched by some demonic being. See, if you actively expand theories, time passes more slowly
