Driving Statistics: 1 In 4 Adults Surf The Internet While Driving

Yes, it is based on a survey - but the results seem plausible based on anecdotal evidence - that 1 in 4 adults surf the internet while driving (Source).

And the details are as expected as well - it is the crowd below 30 that is most distracted. As all phones become 'smart' these numbers would only go up.