Tyre wear V70 D5 enormous

Hello guys, I had to say yesterday when I switched to WR with horror that my summer tyres have only 3mm profile at the front. Well, that may not be special for some people, but I have so far only driven about 20Tkm, exactly one summer long. Is that normal with the D5, that he is leaving the rubber like that? What about other tires manufacturers, with me was still the original equipment replacement Pirellis on it. Greetings Michael