documentclass[11pt,a4paper]{article}
usepackage[utf8]{inputenc}
usepackage[ngerman]{babel}
IfFileExists{MyriadPro.sty}{usepackage[lf]{MyriadPro}renewcommand{familydefault}{sfdefault}}{relax}
usepackage{array}

begin{document}

newcolumntype{L}[1]{>{raggedrightletnewline\arraybackslashhspace{0pt}}m{#1}}
newcolumntype{C}[1]{>{centeringletnewline\arraybackslashhspace{0pt}}m{#1}}
newcolumntype{R}[1]{>{raggedleftletnewline\arraybackslashhspace{0pt}}m{#1}}

begin{tabular}{m{1cm}C{1.3cm}C{1.3cm}R{1cm}}
textbf{W}& textbf{X} & textbf{Y} & textbf{Z} \
hline
textbf{A n.c.} & 23,2 & 23,2 & 33,4 \
textbf{B} & 4 & 5 & 6 \
textbf{C} & 7 & 8 & 9 \
textbf{D} & 10 & 11 & 12 \
textbf{E} & 13 & 14 & 15 \
end{tabular}

end{document}

documentclass{article}
usepackage{booktabs}% http://ctan.org/pkg/booktabs

begin{document}

begin{tabular}{l@{hspace{1cm}}c@{hspace{1cm}}c@{hspace{1cm}}c}
  toprule
  textbf{W} & textbf{X} & textbf{Y} & textbf{Z} \
  midrule
  rlap{textbf{A n.c.}}hphantom{23,2} & 23,2 & 23,2 & 33,4 \
  textbf{B} & 4 & 5 & 6 \
  textbf{C} & 7 & 8 & 9 \
  textbf{D} & 10 & 11 & 12 \
  textbf{E} & 13 & 14 & 15 \
  bottomrule
end{tabular}

end{document}