you are calculating percentages wrong!
XRP got dumped from $0.53 down to $0.43 and that is 18.8%
XLM got dumped from $0.26 down to $0.21 and that is 19.2%
besides the rule is this:
when bitcoin drops, altcoins get dumped hard unless they are on in pumping session.so altcoins may not always even go down! they may actually go up. as it was the case with a couple of them that have been pumping during the past 48 hours.
seems like centralization or semi-centralization in crypto is going to take over one way or the other. I hope not but we shall see soon.
don't confuse pumps with "taking over"!