What kind of fool assumes women must make up 50% of any given field?

School teachers, nurses, child care workers, cleaners, etc are female dominated fields.  Why?  Because these fields appeal to the majority of women.  

If you want women to go to a field, make the field appeal to them.  Usually there are working conditions which turn women away from these fields (IE. lack of human interaction, poor work-life balance, dangerous).

Trying to force women to work in a field they don't like is stupid.