Bitcoin's dominance would be probably close to 100% if we were to exclude all the useless shitcoins and tokens from these crypto rankings lists. I'm personally not concerned at all about the % calculated anywhere - whatever happens, we all know BTC is almost always needed in the end.
The dominance is quite evident in the bull run led by bitcoin every time likewise when the price drops, all cryptocurrency drops including etheruem. What more are we saying if it is sure with the leadership of bitcoin. The price and volume trade is another factor showing the supremacy of bitcoin in the market.