Calculate average annual inflation
The calculation goes like:
Price index @ 1993 =  60  ==&gt; X_{t+s}=0.6
Price index @ 2012 = 100  ==&gt; X_{t}=1
Number of years from 1993 to 2012 = 2012 -1993 = 19 ==&gt; s=19
$100*((\frac{X_{t+s}}{X_t})^({\frac{1}{s}})-1) = 100*(\frac{1}{0.6} ^{(1/9)}-1)=100*(\sqrt[9]{(5/3)}-1)=5.840007284127$