Hi Anh,
If you're just looking from year to year, and depending on how your organization does rollovers, you can easily create a filtered value using the "solicitor display name." For example:
([# of unique package seat key], [solicitor display name])
To get new subscribers, you would filter to exclude "subscription rollover" and to get renewals you would filter to only include "subscription rollover."
I hope that helps,Christine