teenagers and cars

The AA Motoring Trust has gathered information on the number of teenage motorists dying in road crashes in England and Wales and it appears that the figures have doubled in the last 6 years. By cross-referencing government statistics on accidents and driving licences, they showed deaths of 16-19-year-olds per 100,000 driving licences had risen from 9.76 in 1998-2000 to 19.23 in 2004. And the number of 16-19's holding licences in the same period fell from 41% to 26%.
Info from BBC news website here...
So what's going on?