The latest “wireless substitution” report was recently published by the National Center for Health Statistics (CDC).
From the Introduction:
Nearly one-half of American homes (47.4%) had only wireless telephones (also known as cellular telephones, cell phones, or mobile phones) during the first half of 2015—an increase of 3.4 percentage points since the first half of 2014. More than two-thirds of all adults aged 25-34 and of adults renting their homes were living in wireless-only households. This report presents the most up-to-date estimates available from the federal government concerning the size and characteristics of this population.
The complete 13 page report is available here and also embedded below.