@Coloradomama Using Swarthmore’s data pulled from the NSF, since they have no stake in the results. They analyze the top undergrad PhD producers in STEM and other areas. If you scroll down the pages you will see PDFs of undergrad to PhD success rates for numerous disciplines. This is done by percentage. Harvey Mudd comes out at the top, well #2. So you are waaaaaay off. Look closely at the actual schools that send people on to succeed at PhDs and you may be surprised.
http://www.swarthmore.edu/institutional-research/doctorates-awarded