ASPD? 1% or more?

I had an interesting chat and listened to an interesting opinion from a lady in my Sunday School class this morning. I go to a local UU and the Sunday School is really just a "Living the Questions"/philosophy discussion type of class before the service. Anyway she apparently has experience (past) with Sociopathy (I'm guessing a relative, or something) and sense comparing empathy and sympathy was part of our discussion today, she pointed out that some people can't feel empathy. She also went on to talk about a brain study she read about. I pointed out to her that only 1% of the world's population has ASPD. I also have some personal past and present experience with individuals with ASPD and/or similar personality disorders, so I understand her interest. Anyway, she told it's actually 4% but she didn't have a source to back it up. Honestly, I haven't used that many academic resources in my research either anyway, I was just wondering if anyone knows more about the percentage of the world's population being on the ASPD sepctrum? I've also read somewhere that 16% of prison population includes sociopathic/ASPD individuals. Also is there a mild to severe sprectrum of ASPD?