Although we do not create it (and like everything in our existence), there is an answer to this perception, and is quite simple, and everything has to do with our human psychology...

And the best way to understand what is happening, is jumping today directly to these curious observations:

When you have 2 years of age, 1 year for you is the equivalent to having lived the 50% of your life.

When you have 4 years of age, 1 year for you is the equivalent to having lived the 25% of your life.

When you have 10 years of age, 1 year for you is the equivalent to having lived the 10% of your life.

When you have 20 years of age, 1 year for you is the equivalent to having lived the 5% of your life.

When you have 50 years of age, 1 year for you is the equivalent to having lived just a fiftieth part of your life.

Or in other words, as go the years, These are perceived as going faster for the simple fact that these now represent increasingly shorter time lapse in relation to the years you've already lived.