In 2015, the percentage of those 18 to 34 living with their parents was 39.5%, the highest level since 1940 when it was 40.9%. Of course, 1940 was one year removed from the end of the Depression. The rate then fell to an all-time low of 24.1% in 1960 and has slowly risen since with a recent big run-up. The rise is probably due to rising rents and limited credit.