I've never even heard of Cloud Clusters and I've been working for some of the largest hosts in the US for a decade. I highly doubt they have 60 million customers. GoDaddy doesn't have 60 million customers. RAX doesn't have 60 million customers...
60 million records. They could have reseller hosting where one "customer" has 100's or 1000's of sites on their account. Each of those sites is probably a record.