This table reports the number of abortions, in thousands, for unmarried and married women in the United States in 1990 and in 2000.
a. Is the variable "Year" considered to be quantitative or categorical?
b. For the abortions in 1990, find the probability of the woman being married.
c. For the abortions in 2000, find the probability of the woman being married.
d. From 1990 to 2000, did the probability of being married for women who had abortions decrease substantially, decrease slightly, increase slightly, or increase substantially?