An index number simply expresses the value of some variable in any
given year as a percentage of its value in the base year. For example, the
2020 index of steel output of 122.5 tells us that steel output in 2020 was
22.5 percent greater than in 2010. In contrast, the 2020 index for
newsprint output of 93.8 tells us that newsprint output in 2020 was only
93.8 percent of the output in 2010โthat is, output was 6.2 percent lower
in 2020 than in 2010. The results in Table 2-3 allow us to compare the
relative fluctuations in the two series. It is apparent from the values in the
๎