Just a shot in the dark here but the total (both sexes) is close to fifty million. The gender distribution in the general population slightly favors females, therefore 25,500,00 would not be too far off.
The census tabulates live population statistics by gender, race, income, &c. I would suggest that applying those distribution percentages to the 50,000,000 total would yield a fairly close estimate. With the exception of race, there seems to be a disproportionate number of black babies aborted, comparatively speaking.
The Negro Project: Margaret Sanger's Eugenic Plan for Black Americans
Just a thought here, it isn't "Whitey" that's "out to get them", they're doing it to themselves.
One last point, declining native population is not just an American phenomenon. Nearly all European countries are below a self sustaining birth rate and only show increasing population because of a tidal wave of immigration (largely Middle Easterners)
Regards,
GtG
PS Reminds me of the old "Chinese curse":
May you live in interesting times...
Never can catch all the typos!
G