Secondly, my extrapolation came from the daily volume of trade on the exchanges, from what I see on Coinmarket cap and other sources
http://coinmarketcap.com/currencies/bitcoin/#markets
As of time of writing, Ethereum/Bitcoin pair is 20% of bitcoin trade volume. Where Ethereum Classic/Bitcoin pair is another 6.5% of bitcoin trade volume.
Feel free to calculate all of the pairs to see which percent is national currency pairs. This is useful if I was here to defend the "most" assertation, but the point I intended to make stands. Altcoins are fast, more practical to move to exchanges, many people use them.
And finally, 'many people' aren't trading in and out of the currency pairs to acquire goods and services, just for speculation. As such I'll stick to my '5% of the time' statement about when people actually need national currency.