Definitely not zero.. your server gets IPv4 port scanned 2-10 times a day.

CriminialIP, PaloAlto, Shodan, Stretchoid, Techties, Censy, Onyphe, VisionHeight, Internet-measurement, Infrawatch, BinaryEdge, and a bunch of Alibaba Cloud/Digital Ocean/VPN/Tor exit IPs all know which port your SSH server is on.