Researchers: Roughly 60% of Ethereum smart contracts have never been interacted with

A group of researchers from the Northeastern University and the University of Maryland published a paper detailing their analysis of Ethereum's contract topology. The researchers modify Ethereum's geth client to log how users and contracts interact with one another. The researchers collected bytecodes from all contracts published on the Ethereum blockchain for its first five million blocks, covering nearly three years worth of blocks. This is what they found:

• Roughly 60% of all contracts that have been created have never been interacted with. This suggests there are significant amounts of dormant code and cryptoassets on the Ethereum blockchain.
• There is an extremely high level of code reuse and code similarity on Ethereum. The 1.2 million user-created smart contracts can be reduced to 5,877 contract “clusters” that have "highly-similar bytecodes". A high-level of code reuse suggests that bugs or vulnerabilities in contracts could impact thousands of similar contracts that have reused their code.
• In 2017, the average number of transactions per day on Ethereum increased from roughly 40K to over one million. Despite the recent price drop, the number of transactions per day has recently remained stable. Of these transactions roughly 0.01%–0.1% of transactions fail.
• Roughly one-third of contracts are used by other contracts rather than users.

(Source: Analyzing Ethereum's Contract Topology)