Interesting question. I've used Strava for a little over 5 years, so for the last 5 full years,
2016: 5,201.1 miles
2017: 4,060.9 miles
2018: 1,721.9 miles
2019: 946.4 miles
2020: 2,579.2 miles

...which comes out to an average of about 2,900 miles per year. Prior to that I was generally around four thousand miles per year. In 2018 we moved, buying a 60 year old house that's needed a lot of time and effort and took away from my cycling time. Through the first 6 months of this year I had less than 200 miles, but obviously I'm back to a more normal (for me) pace. What changed? Well because I hadn't been riding I'd put on a lot of weight, and when they said obesity was a major risk factor with Covid I decided to lose some weight. I've dropped 40 pounds since July.