Military Information - Time in Service vs Time in Grade for Naval Promotions

I was curious how long it takes to be promoted from one naval rank to another, so I looked it up in terms of the US Navy and found these stats:

ENS to LTJG:  TIS:  2 years.  TIG:  2 years

LTJG to LT:  TIS:  4 years.  TIG:  2 years

LT to LTCDR:  TIS:  9-11 years.  TIG:  3 years

LTCDR to CDR:  TIS:  15-17 years.  TIG:  3 years

CDR to CAPT:  TIS:  21-23 years.  TIG:  3 years

They want their higher-level officers to have much more experience than the minimum time in grade would indicate.  I call BS on Captain Kirk being promoted to captain at age 34.  He should have been a lieutenant commander at most.  :)