Because this "Data" that you speak of isn't true. This article from the Charlotte Lozier Institute says differently.
"Conversely, good research from Eastern Europe where many countries changed their abortion policy after the fall of communism indicate that the incidence of abortion is sensitive to its legal status. Even modest limits on abortion resulted in significant declines in abortion rates. Furthermore, there is good evidence from the United States and Great Britain (Ashton et al. 1983) that abortion rates significantly increased in both countries after abortion was legalized. Furthermore, there is an impressive body of research which demonstrates that a range of incremental, state-level pro-life laws that have been enacted since the
Roe v. Wade decision have reduced the incidence of abortion in the United States."
"There are several reasons why abortion rates increase when abortion becomes legal. Physicians who are willing to perform abortions can publicly advertise. The economic costs of obtaining an abortion decrease. There is some evidence that public support for legal abortion increases once abortion becomes legal. Additionally, when abortion becomes legal, sexual mores often change, resulting in more unintended pregnancies and more abortions. Overall, the existing academic research paints a very clear picture. Legal protections for unborn children reduce abortion rates and save lives."
How the Legal Status of Abortion Impacts Abortion Rates | Charlotte Lozier Institute