equal height for markup

[Adam Good]

Hi,
This should be very simple but I can't find a hint.

Could someone please offer a suggestion...in the snippet below for
some percussion notation I would like for the texts attached to each
note to be horizontally aligned with one another. Now it seems the
height is based on rhythmic value.

Thanks!!!!

Adam

%%%%%
\version "2.12.3"

\paper {
  indent = 0\mm
  ragged-right = ##f
  line-width = 180.0\mm
}

\layout {
}

#(define mydrums '((ridebell default #t  3)
   (cowbell  default #t -3)))

bellstaff = {
  \override DrumStaff.StaffSymbol #'line-positions = #'(-3 3.2)
  \set DrumStaff.drumStyleTable = #(alist->hash-table mydrums)
  \override Staff.BarLine #'bar-size = #2.2
  \set DrumStaff.instrumentName = #""
  \override Stem #'length = #7.5
}

\new DrumStaff {
  \bellstaff
  \drummode {
    \autoBeamOff
    \time 10/8

    \stemUp rb8^"Dum" \stemDown cb16_"te" cb_"ke" cb8_"tek" cb_"ka"
cb16_"te" cb_"ke"
    \stemUp rb16^"Du" \stemDown cb_"me" \stemUp rb8^"Dum" \stemDown
cb4_"tek" cb16_"te" cb_"ke"
    \bar "|"
  }

}
%%%%%