That is a good question. I have not seen any market research on this but if you are experiencing a large amount of breakage there are a few things I know you can look for to try and keep this under control. First look to see if your staff is stacking glasses. If they are whether it be in a glass cooler or when they are bussing a table put a halt to this as quickly as you can. Stacking glass ware does nothing but chip and crack your glasses. Next look to see how your tables are being bussed. They could be stacking obscene amounts of glass ware on trays and in bus tubs. If one of these trays gets dropped that will blow your glass ware budget for the month. Also look to see if your glasses are going straight from the dish machine to the soda fountain, if so you are probably losing alot of glasses due to breakage from cold shock. Warm fresh from the dishwasher glasses dont like being filled with an ice cold beverage before they are given time to cool.