Ok first of all, this is bs... everyone likes tacos and pizza -_- but ummm
If they like pizza, they are somewhere in this row,|dw:1438957735222:dw|
If they like tacos, they are somewhere in this column,|dw:1438957747170:dw|
Which means "likes pizza" and "likes tacos" must be this particular box, ya?|dw:1438957787316:dw|
So I guess the relative frequency would be that amount... divided by the total number, ya?