Blood oxygen saturation (SpO2) estimates the amount of oxygen in your blood as a percentage of the maximum it could contain.
After a period of sleep, a single value is computed from all gathered data.

The "Daily SpO2" files contain the SpO2 values measured per day during sleep.

Values per row:
- timestamp: The time when the sleep period has ended
- average_value: The average SpO2 value computed during sleep
- lower_bound: Lower bound of SpO2 values
- upper_bound: Upper bound of SpO2 values