It can be difficult to definitively say how many wars have ended without a clear victory for one side or the other. Some conflicts may be considered a "tie" or a "draw" by some, while others may be considered to have ended in a victory for one side or the other by others.
There are conflicts that ended in a compromise, a ceasefire, a peace treaty, a power-sharing agreement, or a return to the status quo ante bellum. These type of agreements can be considered as non-victorious wars.
An example of this is the Korean War (1950-1953) which ended in an armistice and not a peace treaty, the two Koreas are still technically at war.
Another example is the Vietnam War (1955-1975) which ended in a North Vietnamese victory.
It would be hard to give an exact number, as the definition of what constitutes a "victory" in a war can vary depending on perspective.