Last year alts rise a lot. I dont know the average percentage. But when I check coins in the market at year 2013 lots of them dead now (too low ranks). probably new tech coins won them (like peercoin, namecoin, ixcoin etc)
Also we are following new ICO s and most of us expecting too much gain from new coins which are not at the market. If our ICO expectations will happen, when they added to market, current market coins will go down. kind of paradox

Most of us invest ICOs aim to get high profit from them rather then for their inovation. So when the profit is fulfilled, it seems no reason for us to hold them. Most of speculations make the altcoins pump and dump and then finally dead like Penny Stocks.