Fig 2. Fitted probabilities (GAM) of summiting vs. climber age for early (1990–2005, red) and recent (2006–2019, blue) cohorts.

Probabilities of summiting declined for climbers older than ~ 40, but recent climbers of all ages had greatly elevated probabilities of summiting relative to early climbers. Solid lines are from local linear smoothing, and the adjacent shading represents the 95% confidence region for the expected summit probability as a function of age.