This fact is not to be alarmed, according to newsBtc, there is much more money flowing in BTC than there is in ETH, however they recognize that there has been a capital flight from Bitcoin to Ethereum.
I think that approximate ratio of 10% has to do with the generation of each of them since the block time in Bitcoin is 10 minutes, and when a block is generated 12.5 bitcoins are created (formerly 25 and With time will fall back to half, is part of the algorithm). Instead in Ethereum the block time is approximately 14 seconds and 5 ethers are created.