I like it but I think the granularity needs to be fixed. For example, the cutoff points should be 21+ months -> 2 years instead of 13+ months -> 1 year.
So basically you want the cutoff to be > 1.66 of the next unit before you display in that unit. That means 40 hours, 2 days; 11 days, 2 weeks; 6 weeks, 2 months; 20 months, 2 years.
