How big is the zero-knowledge proof market?

Excuse me, could you elaborate on the current size of the zero-knowledge proof market? Is it a burgeoning industry with significant growth potential, or is it still in its nascent stages? Are there any notable players dominating the space, or is it a fragmented market with various players contributing to its development? Additionally, how does the market size compare to other blockchain-related sectors, and what factors might influence its future growth trajectory?