I believe there usually are some changes in the previous year's list. Remember that this list is generated from applications for social security numbers. I think that children born in hospitals in the USA almost always get the numbers very shortly after birth because parents are given the forms to fill out by the hospital. However, children that are born at home or somewhere else other than a hospital might not have the application for the number filed until late enough so that their data doesn't get in to the initial May
report. Plus if there is a name change or a correction in an error on the original application, this might get into the database later and affect the totals.