Question: how to calculate percentage of missing data?
Answer: E.g. the number of missing data elements for the read variable (cell G6) is 15, as calculated by the formula =COUNT(B4:B23). Since there are 20 rows in the data range the percentage of non-missing cells for read (cell G7) is 15/20 = 75%, which can be calculated by =G6/COUNTA(B4:B23).