adding data to a new column each day that the worksheet is used

I have a worksheet that creates a list of individuals from imported data based on specific criteria. Each day, this information changes. I am attempting to get the spreadsheet to automatically save the list in a column next to the previous day's data. The imported data has the date on it and I would compare it to the current date ' =TODAY(). If the date was different from the last time the spreadsheet was opened, then the data would then be added in a new column. This would allow me to compare the data over a period of time. Any ideas? I have attached the sample worksheet.