The detailed criteria are on GitHub.

Level Total active MUST SHOULD SUGGESTED Allow N/A Met justification required Require URL Met justification or URL required Includes details New at this level Future
Passing 66 42 10 14 27 1 8 9 48 66 0
Silver 55 44 10 1 39 38 17 54 38 48 0
Gold 23 21 2 0 9 21 3 21 15 14 0

The "active" criteria are criteria that are included in the percentage calculations (as opposed to "future" criteria). The next columns identify the number of active criteria in each level that are MUST, SHOULD, SUGGESTED, allow a "N/A" as an answer, require justification when "met" is the answer, require a URL, require justification when "met" is the answer or a URL, include details, or are new at this level. "Future" criteria are shown on the form, and are expected to be added as active criteria to some level in the future, but are not included in completion calculations.

You can see statistics about projects over time at the project stats page.