Q: This task involves creating questions from a given passage that involve some kind of complex reasoning (including numerical reasoning).
The generated questions must require looking at more than one part of the passage to answer. Try to use a variety of reasoning types in your questions (some of the sample reasoning types are illustrated in the 'positive examples' field) and also have a variety of answer types (spans, numbers, dates). A span is a continuous phrase taken directly from the passage or question. In such questions, the answer spans are recommended to be five words. Questions with answer type "number", are expected to start with "How many". For instance, "How long did an event last?" can be phrased as "How many years did an event last?". To increase diversity, try to create more questions for which the answer will be multiple spans. Please create questions that require AT LEAST 2 arithmetic operations as illustrated in the 'positive examples' field. You are encouraged to try DIFFERENT COMBINATIONS of operations and not just limit to the combinations shown in those examples. The more challenging questions you create, the better it is.
Passage: During the Tang dynasty , a navy town, Tuen Mun Tsan was established in Nantou, which lies across Deep Bay. Tuen Mun and the rest of Hong Kong were under its protection. A major clan, To , brought the name Tuen Mun to the area. They migrated from Jiangxi on the Chinese mainland and established a village Tuen Mun Tsuen late in the Yuan dynasty . As more and more villages were established, the village was renamed Tuen Mun Tai Tsuen , which means "large village" in Chinese. As yet more villages were established, a market town of Tuen Mun Hui was established. This town lies where present-day Tuen Mun Kau Hui is situated. Tuen Mun remained an important town of coastal defence until the start of British rule in 1898. When the British took over the New Territories from the Qing government in this year, the area was renamed Castle Peak, and Tuen Mun Hui to Castle Peak Market or Tsing Shan Hui. The name Tuen Mun, however, continued to be used by those living in the area. In 1965, "Castle Peak New Town" was planned. It was later renamed Tuen Mun New Town and constructed from 1970 onwards with many buildings on the reclamed land of the former Castle Peak Bay. The name was officially changed back to Tuen Mun in 1972. The first public housing estate built in the town was Castle Peak Estate, opened 1971.
A:
How many years after Castle Peak New Town was planned did Castle Peak Estate open?