Well if you're a woman it is. You see women get paid less than men in most countries and industries. The difference varies but according to the International Labour (ILO) Organization women globally are paid about 20 per cent less than men.
80% of the year is 292 days, and that's today. So from today, the women around you (look up and around how many do you see?) are working for free.
What is your organizations stance on this? Is there an equal pay policy? How is it monitored and measured?