The DWP have released a report Disability Living Allowance: Growth in the Number of Claimants 2002/03 to 2010/11  that demonstrates a 29% rise in claimants over the last eight years.

"The number of DLA claimants has grown by 29% over the last eight years (Figure 1).
Essentially the drivers for this growth can be categorised as: changes in the size of the
population; changes in the age structure of the population; the “maturity” of the benefit (this
concept is explained further below); and increases in receipt per head of DLA. This
analysis breaks down the 29% to show how much each factor contributes to the total
growth."

Disability Living Allowance: Growth in the Number of Claimants 2002/03 to 2010/11 

Disability Living Allowance: Growth in the Number of Claimants 2002/03 to 2010/11 (Tables)

You can find much more recent analysis by clicking here.