When you made the purchase a receipt of purchase was issued ... if you did not keep that information and the broker doesn't have it then you will need to figure that out yourself. If it was more than a year ago then you can simply use the word "various" ... but your real issue will be the cost basis ... if the broker doesn't have the date of purchase then they probably don't have that more important info ... again search your records OR give it your best guess ... google search historical pricing.