@ fulhamish: With regard to your first point, do you have figures for the number of "backstreet" abortions performed in the 20 years *prior* to 1968? If you don't, the figure you have quoted is largely meaningless.
That is, if the figures indicated that the number of "backstreet" abortions between 1948 and 1968 was, say, 50,000, then reducing that to less than 1,000 in the 20 years following the change in the law certainly *would* demonstrate the benefit of the law. If, on the other hand, there was evidence to suggest that only about 1,000 backstreet abortions had happened between 1948 and 1968, then obviously the law could be seen to have had little effect.
But to simply quote a figure, as you've done there, without a comparison or baseline to set it against, proves nothing.
I do not think that the issue of backstreet abortions is the main reason for allowing abortions to take place legally, by the way, I'm just saying that your use of statistics is flawed.