There are no published standards or data regarding the shelf life of paper. If the paper is kept sealed in the original wrapper (air and moisture barrier) it should last quite a while. Moisture and trace chemicals (acids) in the air will react with exposed paper, causing it to yellow and become unusable. Archival paper specifications call for a neutral pH and no lignin. Lignin is the brown material in wood that bonds the cellulose fibers. In paper making, the wet pulping and bleaching process dissolves and removes the lignin. Ground wood pulp is made by grinding the wood and the lignin remains. Paper with any ground wood pulp would be less stable over time. Paper with an acidic pH will interact with the lignin and accelerate the yellowing of the paper, especially when exposed to UV light. Most paper is made today with alkaline sizing and has a neutral or alkaline pH. The answer to your question is that it depends on how the paper has been stored, the materials used to make the paper, and how the paper was made, which only the paper manufacture can answer. I did find one reference to shelf life of paper being 10 years.