You need the Total Number of each population or you cannot do it. Your value is much too high.
For example - from baseball:
Given a batting average of 0.250 in April and a batting average of 0.290 in May, there are lots of wrong ways to calculate the batting average for both months, combined.
(0.250 + 0.290)/2 = 0.270 = Wrong!
Hits/At-Bats: April: 25/100, May: 33/114 ==> Average for both: (25+33)/(100+114) = 58/214 = 0.271 -- In this case, just a little higher than the bad way.
Note: In this tiny example, it made very little difference. Don't begin to believe this is always the case. We're just showing that it IS different. Depending on your data, it can be VERY different. Also, if our baseball player has a bonus in his contract for hitting OVER 0.270, he will appreciate the correct calculation. A very tiny difference can mean quite a lot.
Thus, for your question,
1) We are given the Number of Abortions.
2) We are NOT given the numbers of the total populations. If we can't figure that out, we're sunk. We can say something like, "between 0 and 240"
How do you propose to reconstruct the total population? Think about that incidence number. How is it calculated?
Note: "rate per individual woman" doesn't mean anything. Most of those are zero (0) over probably any period, long or short.