Answer (see chart below from Kleiner Perkins): 5 years.

Mary Meeker is out with her annual Internet trends slide deck (300+ slides), which makes for a fascinating read (do you read slides?). I will be interspersing her charts in the weeks ahead. Lots of interesting data and visualizations about the pace of technological change. Here is a chart showing adoption curves for new technologies, both old and new: 

Questions:

• What do you notice about the speed at which new technologies are adopted by U.S. population?
• How can you explain the answer to the first question? Why?
• Why do you think it took 16 years for 1/4 of the population to use a PC?
• What do you think were the barriers to cellphone adoption?
• This chart looks at the speed for a technology to be adopted by 1/4 of the population? How long do you think it takes to get the next 1/4 of the population? Longer or shorter than the first 1/4? Why?
• Which of the innovations above had the most dramatic impact on living conditions?

About the Author

Tim Ranzetta

Tim's saving habits started at seven when a neighbor with a broken hip gave him a dog walking job. Her recovery, which took almost a year, resulted in Tim getting to know the bank tellers quite well (and accumulating a savings account balance of over $300!). His recent entrepreneurial adventures have included driving a shredding truck, analyzing executive compensation packages for Fortune 500 companies and helping families make better college financing decisions. After volunteering in 2010 to create and teach a personal finance program at Eastside College Prep in East Palo Alto, Tim saw firsthand the impact of an engaging and activity-based curriculum, which inspired him to start a new non-profit, Next Gen Personal Finance.

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