The losses vary, so to speak.
In recent years, things have been going much better in Canada, where losses are under 20%. However, losses in certain provinces, such as Manitoba and Ontario, have exceeded 30% in the past five years. The losses aren't equal across the country or from year to year.
In the past three years, the winter mortality rate appears to have lowered. This rate is the easiest to measure. We compare the number of bees that enter the hive in the fall with the number that leave the following year. In the summer, it's very difficult to manage. The estimates are always slightly less accurate.
To answer your question, on average, the losses have exceeded 20% in the past ten years. I think the winter mortality rate in Canada is 24%.