Why Coolant Drops Yearly?

Is it normal for it to drop like a cup...??

A year? Probably normal. The water pump always weeps a tiny bit, hoses can weep a tiny bit, some evaporates from the reservoir. I've only had one car that never looses any coolant, it's got a totally sealed system and isn't driven in winter. My other car with a traditional vented reservoir and cold weather driving drops about a cup a year probably, maybe a little less.