Thirty-one percent (31%) of all domestic cats in the United States are declawed; it is said (source: www.paw-rescue.org – Jennifer Dougherty). Cats are also declawed in Canada. I suspect that the percentage is lower in that country as one province, Nova Scotia, has very recently banned it. This implies that the attitude towards it in Canada is less supportive than in the USA where around 60% of cat owners support it. This is partly (or largely) due to a lack of awareness of the true nature of this grizzly operation (mutilation is the better description) and vets don’t do enough to rectify misconceptions.
I had thought that the figure was nearer 20% but it seems that I was wrong. However, the AVMA (America Veterinary Medical Association) estimate that 25% of cats in the city of Los Angeles are declawed (source: advocatesforfacts.org). I don’t know if LA is a typical city in respect of declawing (It is now banned in that city). This information comes from a National Council on Pet Population Study and Policy which found that 25 percent of all cats in the United States are declawed.
Other than the above, I don’t think there are any clear figures compiled from a formal nationwide survey. The AVMA estimate indicates that.
If there are about 80 million cats in the USA, 31% of that figure is 24.8 million declawed cats.
It appears that the cost of declawing varies enormously from about $60 to about $300. It is a fast operation despite the severity of it (15 minutes?). If we say the average cost is about $100 (conservative price perhaps), the declaw market to vets is worth in total: $2,480,000,000 dollars USD or about 2.5 billion dollars.