  Gender imbalance in information technology in general, and Free/Open Source
Software specifically, is a well-known problem in the field. Still, little is
known yet about the large-scale extent and long-term trends that underpin the
phenomenon. We contribute to fill this gap by conducting a longitudinal study
of the population of contributors to publicly available software source code.
We analyze 1.6 billion commits corresponding to the development history of 120
million projects, contributed by 33 million distinct authors over a period of
50 years. We classify author names by gender and study their evolution over
time.We show that, while the amount of commits by female authors remains low
overall, there is evidence of a stable long-term increase in their proportion
over all contributions, providing hope of a more gender-balanced future for
collaborative software development.
