Generally the number of your friends who have funerals is heavily biased towards the end of your life.
America's average lifespan is 77. When you're 16, your parents are perhaps 46, and their parents are maybe 76.
And a lot of people live for 10+ years after retirement, so your teachers might all be alive too.
If you've got a big extended family, or you're part of an organisation like a church where 16 year olds come are getting to know 70+ year olds, you might have gone to more than 6 funerals.
But generally? At 16 your parents, their friends, your aunts and uncles, your 16 year old friends, their parents? Good chance they're all still alive. Your grandparents - maybe, maybe not.