Tor onion services are a challenging research topic because they were designed to reveal as little metadata as possible which makes it difficult to collect information about them. In order to improve and extend privacy protecting technologies, it is important to understand how they are used in real world scenarios. We discuss the difficulties associated with obtaining statistics about V3 onion services and present a way to monitor V3 onion services in the current Tor network that enables us to derive statistically significant information about them without compromising the privacy of individual Tor users. This allows us to estimate the number of currently deployed V3 onion services along with interesting conclusions on how and why onion services are used.