Since July 2017, I have had a script run daily to collect data on the market cap of tokens from coinmarketcap.com. The script tabulates the total market cap of all tokens, and of all Ethereum-based tokens, and uses these two figures to calculate the share of the total token market cap constituted by Ethereum based tokens.
The script excludes those tokens that CoinMarketCap classifies as ‘low volume’ to limit the data set to assets with enough trading volume to provide reasonably reliable market cap estimates, though the data doesn’t change much when these are included.
The results show that the total market cap of crypto tokens grew from a little under $4 billion, on July 2nd 2017, to more than $68 billion, on January 12th 2018.
Over that six month period, Ethereum-based tokens saw their share of token market capitalization grow from 73.8% to 91.2%, with the market cap of Ethereum based tokens now at over $62 billion (from $2.9 billion at the beginning of the time series).
It’s clear from the data that Ethereum is rapidly establishing itself as the primary crypto-asset platform.
The number of tokens and amount of value now utilizing Ethereum is spurring the creation of a growing suite of software, both off and on chain, for handling ERC20 compliant tokens.
On-chain DApps include decentralized exchanges like EtherDelta and many more under development (for example those using the 0x protocol, like Ethfinex, Radar Relay, The 0cean), and blockchain based lending DApps, (e.g. EthLend, the Dharma Protocol, and Lendroid, which allow ERC20 tokens to be used as collateral for self-executing loan contracts).
In addition to this, the popularity of the ERC20 standard has resulted in centralized exchanges having put in place processes for quickly integrating new ERC20-based tokens.
All of this is making Ethereum increasingly attractive as a platform for projects looking to launch their own token, which likely explains the growing market share.
The token market capitalization chart can be explored in this link.
UPDATE, March 19, 2018:
An updated ERC20 market share chart can be found here.
The market share peaked at 93.15% on January 26th 2018, before beginning a gradual slide to 88 percent, mostly because the market has gone down, and the number two token by market cap, the USD-backed Tether (which is not Ethereum-based), has seen its market cap stay steady.