aggregate they have in recent years obtained an enhanced share of the national income. This is reflected in other ways which spring from the same fundamental principle. The increase in the national income during the 10 years beginning with 1913 is ascribable in only small measure to increase in the national production. It has been due in the main to the writing up of values. In other words the people have not bad the enjoyment of more goods per person, but merely about the same supply expressed in different unit values. If the expressions were uniform for all things the people would be equally well off, but such is not the case.
Index numbers, whereof there are many, show the specific trend of things in nothing but the branch of industry or aspect of life that they represent. Therefore there should be great caution lest they be used for the measurement of things that they do not represent.
| Year | Composite | Railway employees | ||
| Total | Trainmen | Others | ||
| 1913 | 100 | 100.0 | 100.0 | 100.0 |
| 1914 | 100 | |||
| 1915 | 101 | |||
| 1916 | 125 | 115.7 | 113.5 | 117.4 |
| 1917 | 150 | 130.2 | 125.8 | 132.0 |
| 1918 | 165 | 184.1 | 157.2 | 195.7 |
| 1919 | 195 | 192.8 | 168.4 | 205.7 |
| 1920 | 200 | 236.1 | 211.5 | 248.7 |
| 1921 | 170 | 216.0 | 181.4 | 231.8 |
| 1922 | 170 | 216.5 | 188.4 | 228.3 |
