Is Every "Old" House Haunted?

This has always been a topic of discussion in my family. Living in the Philadelphia area. Every place you go there are pretty old houses. Some dating back to the late 1600's. But, there are many built Pre-Revolutionary times. Many people live happily in these homes. I have (as a New Yorker were never scared to ask questions)ask some of these people pruning there flowers in their front lawn as I'm walking my dog,"Do you think your house is haunted?". The answer in many "No". I myself have lived in an apartment house built in the late 19th century. And, slept like a baby. And, hey, these houses are built more solid then the houses built today.
So, I personally believe a house is haunted because of who died there that hasn't moved on. Whether the house is new or old?
My problem is with a lot of these investigations there is going to be some sort of sounds. I mean, household equipment, general settling, heat & cold effects, weather, and critters. Even, household pets (if they are left inside)even if they are inside a aquarium tank. I love when they go into places that are empty. But, some have junk all over the place. Sometimes you walking by the "so call junk" causes something to move. Something wasn't sitting right.
There is another question I have? And, nobody every asked? What is the percentage of places are really haunted? We are made to believe "everywhere" is haunted. Me, as a believer don't believe that.