At what ratio hybrid and unhybrid orbitals are taking part in bond formation in acetylene molecule ?

$$$$\begin{gathered} {\mathrm{C}}_2{\mathrm{H}}_2\Rightarrow \mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H} \\ \downarrow \downarrow \\ \mathrm{sp} \mathrm{sp} \\ \downarrow \downarrow \\ 2\mathrm{HO} 2\mathrm{HO} \end{gathered}$$

No. of Hybrid orbitals=4

No. of pure orbitals=4(two from each 'C')+2(one from each 'H')=6

ratio=4:6=2:3