D&D 5e has slowly increased the number of books per year. Like here are all the official hardcovers by year.
2014: PHB, MM, DMG, Tyranny of Dragons part 1 and 2.
2015: Princes of the Apocalypse, Out of the Abyss, Sword Coast Adventure Guide.
2016: Volo’s Guide, Curse of Strahd, Storm King.
2017: Xanathar’s Guide, Tales from the Yawning Portal Tomb of Annihilation.
2018: Mordenkainen’s Tome, Ravnica, Waterdeep part 1 and 2.
2019: Ghosts of Saltmarsh, BG Descent, Eberron.
2020: Tasha’s Caldron, Wildemount, Theros, Icewind Dale.
2021: Fizban’s Treasury, Van Richten’s Guide, Strixhaven, Candlekeep, Wild Beyond the Witchlight.
2022: Monsters of the Multiverse, Neatherdeep, Radiant Citadel, Dragonlance, Spelljammer.
2023: Bigby’s, Planescape, Phandelver, Book of Many Things, Keys from the Golden Vault.