How long were Jacob and Rachel married?

For various reasons, I've always wondered how long Jacob and Rachel were married before her death. Rachel's death (shortly after giving birth to Benjamin) is record in Genesis 35:16-18. As a result I've always tried to guesstimate the length of their marriage from the age difference between Benjamin and his older brothers, but unless some details are hiding in the original Hebrew that are lost in translation, it doesn't seem to me that there are enough details in Genesis to have any real idea. Is there anything I'm missing? Are there any details that make it possible to estimate (with any accuracy) how long Jacob and Rachel were married before her death?