Ethereum is the best partner of bitcoin, during 2017 ethereum prices were around 5% of the price of bitcoin. when the bitcoin price is $ 5600 then the ethereum price is $ 280
But why since 2018 until now when bitcoin has reached $ 11 707, ethereum is still $ 227. The ethereum price should be $ 585.
What happened

if bitcoin price is $ 20 000 then ethereum price is only $ 600

If you look at the coinmarketcap you'll find out that Ethereum is still the number 2 on the list, Why all altcoins have reduce is due BTC dominance whichbhas increased significantly over the year, This is not a problem caused by Ethereum.