Are you lookng for information about fluctuations in volume or the variety of drinks sold?
CoffeeJunky's experience is similar to mine when it comes to the volume of sales throughout the months.
As far as drink variety goes ......
Winter= lots of hot coffee and not much iced coffee.
Summer= lots of hot coffee in the morning, through lunch time, and then many people switch to iced coffee drinks.
Spring and Fall= both hot and iced coffee based on the weather for the day.
Chilly rainy days= lots of hot coffee
Warm humid days=lots of iced coffee