"Data for families in the first quintile (bottom 20%) are not shown. Their median wealth was as follows: 1989 — $0; 1998 — $0; 2007 - $36 and 2016 — negative $1,099."
BOTTOM 20%. Has has zero or negative wealth. And that has only changed for the worse during the last 30 years.
If one FIFTH of your country has $0 or negative wealth, and your country is the richest country in the world, I would say there is a significant problem.