It is no secret that the classic age of pulp was dominated by male writers.
Yes, there were exceptions (C.L. Moore and Leigh Brackett probably being the most well known, but also Margery Lawrence and Margie Harris and yes, Agatha Christie) but... It's 2018. I would hope that we would see a more equal distribution in writers submitting to us.
And yes, we get it. Action/adventure fiction has long been a male driven market.
And we are two male editors, and that might play a role as well.