OP updated:
- In the first week after the announcement, 286408 posts were made (-19.05%).
- In the second week after the announcement, 280503 posts were made (-20.72%).
- In the third week after the announcement, 259694 posts were made (-26.60%).
- In the fourth week after the announcement, 263685 posts were made (-25.47%).
- In the fifth week after the announcement, 240339 posts were made (-32.07%).
- In the sixth week after the announcement, 240045 posts were made (-32.15%).
Note how close the fifth and sixth week's number of posts are.