the answer to this is subjective. by that I mean there are many people on psych central and everyone is scattered around the whole world. so you will probably get all kinds of answers and most, most likely wont match. example Im in NY , my demographics\statistics are going to be different for say the state of Florida's demographics/statistics. Im in the USA...well the national statistics here are going to be different than that of say in India, or Germany or Japan.

plus statistics\demographics only take into consideration those that are able to get treatment or participate in the periodic census taking of their locations. example there are many people in the USA that have health issues but do not have treatment providers so of course when treatment providers send in their paperwork of how many are on their caseload for their agency to be able to get government help every month that paperwork is not going to include those that do not have treatment providers or have closed their files with that mental health agency. which in turn affects the statistics of how many people have mental illness in one city/town/state, nation.

another thing to consider some treatment providers are specialists, they only treat this or that, so of course their statistics on how many clients they have on which mental disorders is higher is going to be based not on actual how many in the USA have that mental disorder, but rather how many they treated that month with that mental disorder. one place may treat 100 people with depression and only a handful of PTSD where as the VA may treat 100 with PTSD and only a handful with just depression...

see what I mean. you may want to narrow define your question to something that will be able to give you a definitive answer like for example a certain location, date, time frame, ..how many people are treated for mental illness last month is your location,

heres another idea. contact a mental health agency in your location. they will be able to tell you what your area's present statistics are. your local library can also tell you that information for your direct location. this way you will have accurate information as it pertains to you and your location and why you need this information.