An estimated 5% of the American population own a Tablet device

"Of all the wireless devices that have hit the market in the past several years, tablets present the biggest commercial opportunity for media owners, in terms of what consumers are willing to pay for and consume on the devices. But for now, that opportunity is, at best, a mid-to-long-term one. Research from Nielsen—being presented for the first time today at the paidContent Mobile conference—shows that in the U.S. today, more than 95 percent of consumers have yet to buy one.
Despite the huge amount of hype that has surrounded the iPad and the many other tablets hitting the market—they include Android-based devices, the recently-launched Playbook from RIM (NSDQ: RIMM), and the soon-to-come TouchPad from HP —the researches note that as of Q1 2011, only 4.8 percent of the roughly 12,000 U.S. consumers surveyed have bought one. That number is likely even smaller in most other markets, even developed ones. Paul Lee, an director of TMT research with Deloitte in the UK, estimates that in the UK the number of tablet users is 1 out of every 60 people—or 1.7 percent."

Source:  Research from Nielsen and Deloitte (separately), reported by PaidContent, 18th May 2011

Note - Bear in mind that before the iPad almost no one had a Tablet, so since April 3rd 2010 nearly 5% of the US population have one.  This is meant to be a bad performance?  

Look at this chart from The Mobile Internet Report Setup by Morgan Stanley in December 2009 (chart 42) which shows the comparative adoption of technology devices including the iPod, Wii, Blackberry and so on.  All had exposure disproportionate to their sales in the early days, but all were very influential.  

Click to enlarge