The worst recent flu of 2017/18 led to a yearly average excess death in the Netherlands of 1.5 daily excess deaths per million (DEDpM), with epidemic weeks reaching over 5 DEDpM. A cutoff for severe excess death could be set at 5 DEDpM as a comparative tool.
Here is a contrast of a nation with a younger population (Armenia) vs. a nation with an older population (Sweden):
Reference
[average daily excess death during 2018 in the Netherlands was 0.15 per 100k (1.5 per million); peak daily death was 0.99 per 100k (9.9 per million)] — van Asten L, Harmsen CN, Stoeldraijer L, Klinkenberg D, Teirlinck AC, de Lange MMA, Meijer A, van de Kassteele J, van Gageldonk-Lafeber AB, van den Hof S, van der Hoek W. Excess Deaths during Influenza and Coronavirus Disease and Infection-Fatality Rate for Severe Acute Respiratory Syndrome Coronavirus 2, the Netherlands. Emerg Infect Dis. 2021 Feb;27(2):411-420. doi: 10.3201/eid2702.202999. Epub 2021 Jan 4. PMID: 33395381; PMCID: PMC7853586. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7853586/