What I was asking for is quite objective.
Basically, since Roe v. Wade, how many babies have been aborted, broken down by race? Then, if they had lived to adulthood, if the typical number themselves had children there would be even more people.
Though the majority of aborted babies were white, still the number of aborted black babies was significantly higher than the percentage of the American population that are black.
In turn, this means that there would be many more black Americans than there are right now. Right now, 12% of Americans are black. Were it not for Roe v. Wade, it might be 13, 14, or 15%.
About 15 million abortions were undergone by black women, about 30 million abortions by non-black women from 1973 - 2004 In 2004, the black population was about 36 million and 12 percent out of a population of about 300 million.
If we increase the numbers by the number of abortions performed, then blacks would be at 51 million, non blacks at 294 million, total population at 347 million, assuming that immigration, both legal and illegal remained the same, a dubious assumption.
Given those numbers the percent of black people in the population would be 14.7 percent. If fewer people had immigrated, the percentage would be higher.
Source for the numbers: