My house was built in 1988, I have a 20 AMP Siemens GFCI in the breaker box protecting four outlets. Two of the outlets are at the kitchen counter three feet left and right of the kitchen sink. The other two outlets are in the hallway on the other side of that kitchen wall. About 2 1/2 years ago I started finding that breaker tripped every couple weeks. The time interval of it tripping kept getting shorter and after six months it was tripping every two days with nothing ever plugged in to the outlets. I pulled out all four outlets and inspected them for cracks or loose wires. No problems found so I bought a new breaker and installed it. Everything was fine for about 18 months and then it starting tripping again every week or so. As time went on the trips got more frequent. I replaced all four receptacles but it still trips every few days never with anything plugged in. I can reset the breaker and use the outlets to plug in a blender and make a smoothie or plug in a coffee pot and make coffee with no problem but then I will find the breaker tripped again a day later while nothing is plugged in. All walls and wires are dry, no moisture. Any suggestions greatly appreciated. Thanks, Boji