According to Trends in the Characteristics of Women Obtaining
Abortions, 1974 to 2004, tables 3 and 4, and Statistical Abstracts of the United States 2012, table 101, abortion data is as follows:
year: non-whites (blacks)
1973: 195,820
1974: 269,250
1975: 333,000
1976: 394,410
1977: 427,920
1978: 440,190
1979: 435,270
1980: 460,260
1981: 469,570
1982: 478,660
1983: 490,640
1984: 490,550
1985: 512,910
1986: 529,300
1987: 541,800
1988: 565,080
1989: 546,990 (495,680)
1990: 569,890 (505,270)
1991: 574,480 (506,790)
1992: 585,400 (516,890)
1993: 587,280 (517,130)
1994: 567,170 (491,590)
1995: 542,250 (462,470)
1996: 563,300 (482,740)
1997: 557,990 (479,360)
1998: 557,120 (475,720)
1999: 572,240 (484,780)
2000: 580,300 (488,040)
2001: 574,460 (475,700)
2002: 563,170 (467,580)
2003: 555,460 (458,320)
2004: 548,270 (453,040)
2005: 544,000 (452,000)
2006: 561,000 (464,000)
In other words, data for blacks aborted was only collected from 1989-2006, during which 8,677,100 were aborted.
Prior to 1989, data for non-whites was lumped together, meaning blacks, Asians and native Americans. From 1973-1988 this adds to another 7,034,630 aborted, the vast majority (90% based upon 1989 data) of whom were black.
So about 15 million blacks were aborted in the United States from 1973 to 2006.
And yes, this greatly exceeded all causes of death of blacks in this time period, as seen in table 1 of Deaths: Final Data for 2014. Deaths of blacks never exceed 292,808 in any year from 1973-2006.