The plot below shows kilometers per year bicycled for the past 4 years. The exercise log software that came with the Polar HRM, along with the download of stats from the monitor, make this and other information fairly easy to keep track of, even when the HRM is in the shop for new batteries and other(?) periodic maintenance.
Mileage is down since the job change of two years ago; but, not fatally so. Exercise time is more stable over this period.