How many bottles of shampoo do you get through in a year?

I am trying to make a budget and calculate how much a years worth of shampoo costs, I am particularly interested in how much a family of 4 or 5 would use per yearHow many bottles of shampoo do you get through in a year?
WE GO THOUGH MAYBE 40 AND WE R A FAMILY OF 5 AND ONE IS BABY SHAMPOO AND CURLY HAIR SHAMPOO AND SUSILK FOR WHEN WE STRAIGHTEN OUR HAIR !!!How many bottles of shampoo do you get through in a year?
I don't know but me and my fiance go through a bottle about every week. I have long hair.
30ish i guess