2006 broadband penetration data.
"Over Half of US Households Subscribe to Broadband - US Broadband Penetration Grows to 82.2% Among Active Internet Users - June 2007 Bandwidth Report
Broadband services now account for about 72% of all home Internet subscriptions - compared to 60% last year. Broadband adoption is strongly tied to household income. Just 45% of households with annual incomes below $30,000 subscribe to an Internet service at home - compared to 92% of households with annual incomes above $75,000. Broadband penetration among active Internet users grew to 82.18% in US homes in May, up over 10 percentage points from 71.76% last year."