No, I took the government xls datafiles.
Anyway
Table H-1. Income Limits for Each Fifth and Top 5
Percent of All Households: 1967 to 2015
(Households as of March of the following year. Income in current and 2015 CPI-U-RS adjusted dollars (28))
Year =C108/B108
Year = Lowest/"Number (thousands)" = % of the total
the lowest 1/5 (20%) count is declining.
in thousands
https://www2.census.gov/programs-sur...olds/h01ar.xls
Here is the real data and a real graph. The lowest 20% is almost static while the households number count has increased over the years. Look at the lowest 20% of household income.