199 1 how much is a dollar coin worth every year? What's the pattern like?

This is a commemorative coin issued by 199 1 for the "70th anniversary of the founding of the Party". A full set of 3 commemorative coins, each with a denomination of 1 yuan, and the front design is: an old site, Zunyi Conference and the Third Plenary Session of the Eleventh Central Committee. Coins are made of copper-nickel alloy. The circulation of this coin is 30 million sets, which is a variety of commemorative coins circulating in the early and middle period. It is very common in the coin market and has little appreciation potential. At present, the retail price of each set of commemorative coins is about 25 yuan. Your only item is Zunyi Conference, which is incomplete and worth about 7 yuan. I hope I can help you. . .