You have to jump through a hoop or two to translate between definitions of median income, but here’s a rough cut.
For median household income, US data shows that Mississippi is at 70% of the national average.
For cross country comparisons, the OECD tracks a more technical statistic, the average household net adjusted disposable income per capita. By this measure, France is at US$34,375 a year. The US is at US$ 51,147 a year. So France is at 67% of the US average.
Note that the OECD’s “average household net adjusted disposable income per capita” includes social benefits, so if France has a more generous social safety net, that actually juices its numbers up.
Wikipedia has a table on “median equivalent adult income” which does some more adjustments like normalising for household size. In this measure, France sinks even lower to around 60% of the US.