They state that variables Examination and Education are averages for 1887, 1888 and 1889.
Project “16P5”, pages 549–551 in
Mosteller, F. and Tukey, J. W. (1977) Data Analysis and Regression: A Second Course in Statistics. Addison-Wesley, Reading Mass.
indicating their source as “Data used by permission of Franice van de Walle. Office of Population Research, Princeton University, 1976. Unpublished data assembled under NICHD contract number No 1-HD-O-2077.”
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
pairs(swiss, panel = panel.smooth, main = "swiss data",
col = 3 + (swiss$Catholic > 50))
summary(lm(Fertility ~ . , data = swiss))