The reason to combine data:
Combining data of two or more categories is a way to reduce the total number of words you need to write to make sure you can write a good task response in 20 or so minutes you have to write your report. In addition, it is a good way to write more complex sentences to increase your grammar. Below is an example of how you can combine data. The word respectively is a useful word.
Beef and lamb showed a similar significantly downward trend throughout the period. Beef and lamb started at 220 and 150 grams, respectively; and by the end of the period they plunged to approximately 120 and 60 grams, respectively. Beef sales peaked at about 240 grams in 1984. Lamb reached a low point of about 55grams in 2000.