how to assign the same number of rows to each case based on years
I have a vertical data set with uneven number of years' data (body weight, for example) for each case. Some have years 1,2,3,4,6 and some have 3,4,5. I want each case to have 6 rows with the year column containing 1,2,3,4,5,6 even though some of those years will not have a body weight. How can I assign each case 6 rows that recognize the appropriate missing year?