美国签证数据来源与引用
主要来源：美国国务院 Nonimmigrant B Visa Adjusted Refusal Rates by Nationality；美国国务院 Global Visa Wait Times。国家概览（人口、首都、地区）在可得时来自世界银行公开数据。护照概览在展示时引用所列官方外交部/政府来源，仅供参考。
How often each source moves
- Wait times: when the official appointment table changes.
- Adjusted refusal rates: with the fiscal-year publication.
- Passport mobility: reference table, separate from wait times.
- Country indicators: World Bank releases.
Data update policy
Each source has its own clock. Wait times follow the State Department page when that page changes. Adjusted refusal rates change when a fiscal-year table is published, not on a 45-day timer. Passport tables are reference data on a slower review cycle. Country indicators follow the World Bank release calendar. A page is not marked stale just because another dataset moved.