A doubt on the Regression of Mankiw, Romer, Weil 1992 paper
I had a look at the data, and it is like @denesp says in his comment: e.g. a $2.60\%=0.0261$ population growth rate is written as $2.60$, a $24\%=0.24$ investment-to-output ratio is written like $24.0$, etc. 
So they must be divided by $100$.