In 1700 the official exchange rate was adjusted to 1 ryō equal to 60 "monme" silver (225 grams) or 4000 brass coins. Tokugawa Yoshimune further conducted a reform to stimulate the economy and raise prices in 1736, again lowering the gold content of the "koban". One "ryō" was also considered equivalent to 1 "koku" of rice, or the amount of rice needed to feed one person for one year, although this was a less exact standard, which fluctuated depending on the abundance of the rice crop in any particular year. On June 27, 1871, with the introduction of currency reforms after the Meiji Restoration, the "ryō" was abolished, and replaced one-for-one with the Yen. These fluctuations in the gold content of the koban over time, as well as differences in the cost of living between various points in the Edo period and in modern times make any attempt to relate the value of one ryō in terms of modern currency very difficult. Japanese middle school textbooks often state that one ryō was approximately equivalent to 100,000 Yen at the start of the Edo period, and around 3000–4000 yen at the end of the Edo period. On the other hand, the Currency Museum of the Bank of Japan states that one ryō had a nominal value equivalent 300,000–400,000 yen, but was worth only 120,000–130,000 yen in practice, or 40,000 yen in terms of rice.