chordmode above bar numbers ?

[karl]

In the example below, is there any way to make the bar numbers to be 
below the chord symbols ?

I guess I have to move the bar number engraver from score to staff 
level, or is there another way ?

===========================
\version "2.18.0"

Mch = \chordmode {
  s1 |
  g1 |
  d1 |
}
Ma = \context Voice = Va \relative d'' {
  \set Score.currentBarNumber = #211
  R1 |
  d4 d d d |
  d4 c b a |
}
\score {
  <<
    \override Score.BarNumber #'break-visibility = #end-of-line-invisible
    \override Score.BarNumber #'self-alignment-X = #-1
    \new ChordNames { \Mch }
    \new ChoirStaff <<
      \new Staff \Ma
    >>
  >>
}
===========================

Regards,
/Karl Hammar

-----------------------------------------------------------------------
Aspö Data
Lilla Aspö 148
S-742 94 Östhammar
Sweden
+46 173 140 57