I believe something like 40% of applicants get approved eventually. (Not sure what year those figures are from). Most have to appeal, usually up through court. The first appeal is supposed to mostly be a formality. The court appeals are approved at 75% according to what I just read.

The number may have gone up and it varies by state (which shows the process has issues). Back when I applied applications were up because of the recession and people were applying for disability out of desperation.Since my state was hit hard by the recession they were up to 3 years behind in appeals and were doing appeals on skype with judges from other states to catch up.

Applications in general are way up still as baby boomers age and that is stressing the whole system. Unless a way is found to move money around in 2016 there will be 20% cut in pay for everyone because of lack of funding. HOw that will happen is still being debated as far as I know. The scary thing is that I've written to my congressmen and they don't fully understand all the issues related to this so they don't know how critical it really is.