So far in 2020, we've been averaging about one per month (and if you go back to the initial release in December, we've actually had 13 individual drops in three months, making the average closer to four drops per month since the series was announced), although the average is somewhat complicated by how you count themes that come with multiple drops, like the original Theros Gods during Worlds in February (technically, the Gods were five individual but related drops, although there is an argument for counting them as one big drop since buying all of the drops together was an option)
Academic Dispute Academy Raider Accelerate Akki Ronin Akki Scrapchomper Akoum Flameseeker Aleatory Amber Gristle O'Maul Ambitious Assault Ancestral Anger Arterial Alchemy Artist's Talent Ashling, Flame Dancer Ashling, Rekindled Axiom Engraver Balduvian Rage Battlefield Scavenger Bedlam Reveler Belligerent Guest Bestial Fury Big Score Big Wheel Bitter Reunion Blindblast Blood Petal Celebrant Blood Sun Bloodfire Mentor Bloody Betrayal Boiling Blood Boundary Lands Ranger Brand Brass's Tunnel-Grinder Burning-Tree Vandal Burnout Case of the Crimson Pulse Chandra's Defeat Chandra's Regulator Chandra, Spark Hunter Change of Fortune Chaotic Strike Charging Strifeknight Charming Scoundrel Clamorous Ironclad Cleansing Wildfire Cloudpiercer Common Iguana Conspiracy Theorist Cool but Rude Crash Through Crimson Wisps Cunning Maneuver Curse of Chaos Day of the Moon Decaying Time Loop Decree of Annihilation Deem Worthy Demand Answers Demonic Ruckus Desert Cerodon Desperate Ravings Destructive Digger Discerning Peddler Dismissive Pyromancer Dragon Mantle Drannith Stinger Electric Revelation Ember Shot Enthusiastic Study Epiphany Storm Exocrine Expedite Explosion of Riches
Note that the cards second ability triggers when you sacrifice a Treasure for any reason, not just to activate its mana ability
However, this card helps that process by creating treasures if at least one of your creatures deals damage to an opponent
That's because persist checks the creature's existence just before it leaves the battlefield, and it still has all those counters on it at that point
