Out of curiosity, has anyone produced a chart showing the share of the cryptocurrency market represented by Bitcoin versus a basket of other cryptocurrencies (say, the top 10 or 20 of them)?  It would be interesting to know whether this number was relatively constant, or changing up or down with time.  I think it would be somewhat labor intensive to produce such a chart due to the volatility of the altcoin markets, but I've been surprised before by the data sets people here have put together.