Complex sentence: In 1948,10--15% of science fiction writers were female; women's role in speculative fiction (including science fiction) has grown since then, and in 1999, women comprised 36% of Science Fiction and Fantasy Writers of America's professional members.
Split into simpler sentences: In 1948,10--15% of science fiction writers were female. Women's role in speculative fiction (including science fiction) has grown since then, and in 1999, women comprised 36% of the Science Fiction and Fantasy Writers of America's professional members.