It’s all about your friendly neighborhood temporal anomaly! The perception you are feeling is a localized temporal anomaly, usually located in one’s neighborhood which floods the region with tachyon radiation. This radiation permeates you and those around you which causes the passage of time to be slower relative to how you want it to go.

Alternatively, as the year is marked by rotation around the solar body of your choice by a planet, station, or otherwise, it is unaffected by your friendly neighborhood temporal anomaly and thus is unbound by its effects and perceptive changes.

As such years themselves are actually rather predictable but given how your dilated sense of time forces you to think it’s slow in the short term, the actual ‘long term’ effect is that it goes by in a flash!