75% in 2-12 weeks. 90% of disc herniations are treated without surgery. Most get better within 12 weeks. This is why 12 weeks of non op care is recommended as most will get better or be improving during this time period. The next 15% take longer and 10% are treated by surgery. There is a 5% recurrence rate with or without surgery of another disc or same disc herniating.
HNP recovery. Assuming lack of nerve or spinal cord compression, the ruptured disc may on it's own gradually dry out or dessicate, and shrink profoundly over a 9-10 month period. European MRI studies have substantiated the likelihood of improvement without surgery in many patients with this spontaneous development.