To view product subtotals over a year, start by adding the 'Product Subtotals (Signed)' Custom Column to your Projects list view.
You can then filter by a specific date and hover over the 'Product Subtotals (Signed)' Custom Column to view this total across projects.
If you need to compare these totals to a different year, simply change the dates in the 'Specific Dates' filter.
Pro tip: check the box for 'Include Archived Projects' to ensure all projects are included within a specific date range.