The definition of \finger markup is bad

[Bertalan Fodor]

The definition of \finger markup is bad. The numbers are too small and 
I'm not sure if they are typeset with the number family.

see:

http://lilypond.org/doc/v2.3/Documentation/user/out-www/lilypond/Fingering-instructions.html#Fingering-instructions

\bookpaper {
   linewidth = 160 \mm - 2.0 * 9.0 \mm

   
   indent = 0.0\mm
   raggedright = ##t
}
\paper { 
}


   {
       c'4-1 c'4-2 c'4-3 c'4-4
c'^\markup { \finger "2-3" }
   }