The Following Are the Two CPI Series (One for 1985-1989 $\text { Consumer price index with different base periods, Australia }$

The following are the two CPI series (one for 1985-1989 with base 1980 = 100 and the other for 1989-1992 with base 1990 = 100) published in various issues of ABS publications. Create a new CPI series for the period 1985-1992 with 1990 as the base year. $\text { Consumer price index with different base periods, Australia }$
$\begin{array}{|c|c|c|}\hline \text { Y ear } & \begin{array}{c}\text { Base period } \\(\mathbf{1 9 8 0}=\mathbf{1 0 0})\end{array} & \begin{array}{c}\text { Base period } \\(\mathbf{1 9 9 0}=\mathbf{1 0 0})\end{array} \\\hline 1985 & 148.7 & \\\hline 1986 & 162.6 & \\\hline 1987 & 174.5 & \\\hline 1988 & 187.3 & 95.0 \\\hline 1989 & 202.3 & 100.0 \\\hline 1990 & & 105.3 \\\hline 1991 & & 107.3 \\\hline 1992 & & \\\hline\end{array}$