In 2015 sales of all 3 types of fast food increased dramatically.
This is a common error. Unfortunately there is no information about change in 2015, only from 2005 to 2015:
- Between 2005 and 2015 sales of all 3 types of fast food increased dramatically.
If you are not specific about the time frame then your reporting of data will be inaccurate and you will receive a low score in IELTS for Task Achievement.
Before you write, decide exactly when the change happened and design a suitable time expression. These are the most commonly used:
- from time 1 to time 2
- between time 1 and time 2