I believe that chart is using the governemnt's CPI to calculate the 'inflation adjusted' part. You can find all sorts of academic criticism of how CPI doesn't

I believe that chart is using the governemnt's CPI to calculate the 'inflation adjusted' part. You can find all sorts of academic criticism of how CPI doesn't accurately reflect inflation (most notably of housing/rent prices), which is now the lion's share of a family's expense in the United States.