Here a few citrange and citrumelo zygotic seedling percentages.
Citrus Genetics, Breeding and Biotechnology
edited by Iqrar A. Khan
Page 144, Table 5.1 gives a list of rootstock zygotic percentages including citrumelos and citranges. A search for book preview gave a number of percentages.
Off the top of my head from other sources: C-35 citrange 15% zygotic, Benton citrange 0 % zygotic, Carrizo/Troyer citrange +/- 1% zygotic, C-32 citrange +/- 10% zygotic. Sanford,Yuma, and Phelps citranges have high percentages of zygotic seedlings. Sacaton citrumelo has fairly high percentages also.