No data appears to be attached. Your description, and to be anything like the picture in the document attached, the Relative growth percentage would be your Y axis, not strain. Strain would be group variable. Still can't see how that "week" stuff works as no spread sheet attached and would reshape the data so your  values are like   Strain RelativeGrowth WeekNumber (or actual date)   Note, in general spreadsheets are poor instruments for data interchange because 1) users often violate good data normalization practices (in this case multiple columns for the same data with actual data in the column heading) and 2) cells have no constraints as to data types, resulting in  columns mixing numeric character and other forms of data. ... View more