This table is a useful “ready reckoner” for looking at reported death rates per million inhabitants vs an average infection fatality ratio and the likely percent of population infected. (Note: the average infection fatality ratio is sensitive to the age profile of the country AND the age demographic that Covid-19 has spread within that country). The “Deaths per Million” metric is in common usage in comparisons of countries or states. (e.g. www.realclearpolitics.com/coronavirus )
There are a number of ways to use the table:
a) if you have a point of view on the infection fatality ratio, and know how many covid deaths per million your country/area has experienced, you can read horizontally and estimate the percent to the population that has been infected. (Yellow highlight. See US example for more details).
b) If you have an estimate of the percent of population infected (e.g. from antibody testing), and know how many covid deaths per million your country/area has experienced, you can read down a column and estimate the infection fatality ratio for the infected population. (See Sweden example).
c) If you just have a covid deaths per million number for your country/area, you can look at what that might imply for infection fatality and percent infected.