1step,rule,n_before,n_after,n_removed,rationale21,Combined most-recent-vintage monthly series 1947-01..2026-09 restricted to window 2001-01..2026-09,957,309,648,Window defined by the task32,Drop window months without computable g_t (P_t or P_{t-12} missing in sources),309,308,1,No interpolation/imputation allowed; missing: 2025-104