The 1907 Panic, the Great Depression and the Dot com bust

What so they all have in common?

• The from 1905 to 1915 there was a two order magnitude in the number of telephones and their reach.
• From 1926 to 1934 there was a two order magnitude increase in radio receivers.
• From 2001 to today there has been an exponential growth in on line sales.