There's a ton of information to poke around at the link; but here's their [EDIT] median estimated IFR by age range:

15-24: 0.0032%

25-44: 0.018%

45-64: 0.28%

65-74: 1.8%

75+: 16%

The last one looks similar to the measured death rates by age group in Germany -- i.e., the COVID-19 deaths of 80+ in Germany divided by people tested positive in Germany was around 18% when I looked before, IIRC.

So nearly the entirety of the "1-3% fatality" comes from the fact that it's so incredibly deadly to the elderly.

The overall death rate for 2020 will probably be even below 1%. The old will still die, but the young are no longer driving, smoking, etc and social distancing is preventing other diseases like the flu.