Here’s how long it took for each of the following technologies to reach 50 million users worldwide:

• The telephone                       75 Years
• Air travel                                   68 Years
• Automobile                             62 Years
• Light Bulb                                46 Years
• Radio                                          38 Years
• Television                                 13 Years
• Credit Cards                            12 Years
• Cell Phones                             12 Years
• Internet                                        4 Years
• Facebook                                 3.5 Years
• Twitter                                          2 Years
• Angry Birds (space)            35 Days

While the above stats make the point that technology has generally been diffusing into our daily lives quicker than in the past, a few caveats are in order:  (1) The worldwide population is much bigger now than in was when some of the earlier technologies like the telephone made their debut.  50 million users was a much bigger deal 100 years ago. (2) It can be quite difficult to mark the beginning of a technology.  Did the internet begin in the 1980s when it was just a Dept of Defense project or in 1993 when it was publicly available?  Thus, while the above stats are instructive, they are far from precise and a number of different sources have different time-frames to 50 million users.

Another interesting view is the penetration rate of various technologies into our households by percentage.  Here’s a chart:

How many years to reach 50% (in blue) and 80% (gold) of the US population is interesting as well. Chart is as of 2012: