Correct, see http://www.fas.org/sgp/crs/misc/R40545.pdf . You'll note that even for the lowest quintile this is a decline of over 50%. It would be higher if you just looked at constant consumption, but we don't do that, because our societal consensus is that poor Americans in 2014 do and should treat as standard what Americans in 1960 treated as luxury, including most relevantly, having other people cook for them.

This is because, and I know this statement is controversial, America is radically wealthier at all levels in 2014 compared to 1974.