Neville: There’s no statistics for the Litvaks either. Statistics equally don’t exist for MO, Litvaks or Chasidim.
The population having a smaller growth rate may mean it isn’t as noticable, but proportionally it is equally as applicable.
Why in the world would you assume the MO might have a smaller age gap than the Litvaks? The MO date on their own; Litvaks through shadchanim. Guys picking their own girls will generally pick younger girls.
BTW, the age gap exists by the goyim too.