Looking for sister birth 1975 or 1976????

I am an adoptee looking for a sister who was also adopted. She may not even know that I exist. I was born November 27, 1974 in Belleville Illinois through Lutheran Child and Family Services and think she may have been also. She is about a year younger than me so it is possible that she may have been born in 1976. Her adpotive parents lived in Waterloo at time of placement. If you have any information it would be greatly appreciated.