Absence of Denarius implies the third scroll has already been opened in Revelation 6?

The Revelation that Jesus Christ gave to his servant John describes a series of seven scrolls and seven trumpets that precede the end of the age. The scrolls are opened and in the first four, John is told by each of of the four living creatures to go and see and he sees riders on **differently colored horses**. The first horse is **white** which goes forth to conquer and conquering. The next horse is **red** and it's rider is commanded to take away **peace** from the world so that a world War may happen and cause many inhabitants of the earth to die. The third horse is **black** and the rider of this horse is commanded to cause **scarcity** on the earth such that a quart of wheat should cost a **denarius** and three quarts of barley should cost a denarius. Since this **currency** is no longer in use, is it safe to conclude that this event already happened? In the modern context, the red horse causes an event similar to a nuclear warfare and then after this **scarcity** which brings about **inflation** but the currency described in this verse aged away with the Roman Empire, so has this event already happened?