These are statistics, usually quoted during morning breakfast radio, current affairs shows and by people butting into your conversation, have no real basis and are note scientific by any stretch of the word.
Usually, these statistics are versions of real statistics, with only the most inflammatory parts cherry-picked out of the real statistics to create a sensationalist response from those that hear it.
Woman: "Did you hear on the radio this morning, 87% of housework is done by women; you men are so lazy!"
Man: "O.K., so did it include around the house jobs like cleaning the gutters, mowing the lawn, gardening, car maintenance and opening pickle jars for you women?! That's just hocus-pocus and tabloid statistics!"
Woman: "No, why? Is all that important?!"
Man: *head explodes*