First off, Bulgaria has 7.128 million people in it, and only 15,035 cases of Autism:
https://www.google.com/search?q=population+in+bulgaria&oq=population+in+bulg&aqs=chrome.1.69i57j0l5.3083j0j7&sourceid=chrome&ie=UTF-8
and
http://www.rightdiagnosis.com/a/autism/stats-country.htm

So doing the math, Autism in Bulgaria is at 0.0021%, which if the US has the same rate would put the total number of cases in the US at 658,097, but we currently only have 587,310, so we are only a little better than them. Our factor is 0.0019%.

Vaccines do not cause autism. Sorry, they just don't.
https://www.autismspeaks.org/what-autism/learn-more-autism/what-causes-autism