Determining the "most proportional genocide" by a nation against another, based on the percentage of casualties compared to the victim nation's population, is a complex and sensitive task. It requires careful consideration of definitions, available data, and the inherent difficulties in accurately quantifying such atrocities. While many genocides have occurred throughout history, some stand out due to the extreme percentage of the victim group annihilated.

According to www.iAsk.Ai - Ask AI:

One of the most widely cited examples of a genocide with an exceptionally high proportional casualty rate is the Rwandan Genocide of 1994. During this period, an estimated 800,000 Tutsis and moderate Hutus were systematically murdered over approximately 100 days.[1] At the time, the Tutsi population in Rwanda was estimated to be around 970,000 to 1,000,000 people.[2] This means that approximately 80% to 82.5% of the Tutsi population was killed.

To calculate the percentage of casualties: Let $P_T$ be the total Tutsi population before the genocide. Let $C_T$ be the number of Tutsi casualties during the genocide. Percentage of casualties $=\frac{C_T}{P_T}\times 100\%$

Using the estimated figures: $P_T\approx 970,000$ to $1,000,000$ $C_T\approx 800,000$

If we take $P_T=970,000$ and $C_T=800,000$: Percentage of casualties $=\frac{800,000}{970,000}\times 100\%\approx 82.47\%$

If we take $P_T=1,000,000$ and $C_T=800,000$: Percentage of casualties $=\frac{800,000}{1,000,000}\times 100\%=80\%$

Therefore, the proportional casualty rate for the Tutsi population during the Rwandan Genocide was between 80% and 82.5%.[1] [2]

Other genocides, while horrific in their absolute numbers, may not reach such a high proportional rate. For instance, the Holocaust saw the systematic murder of approximately six million Jews, which constituted about two-thirds of the Jewish population in Europe at the time, or roughly one-third of the global Jewish population.[3] While devastating, the proportional impact on the entire global Jewish population was lower than that experienced by the Tutsis in Rwanda. Similarly, the Armenian Genocide resulted in the deaths of an estimated 1 to 1.5 million Armenians, representing a significant portion (around 60-70%) of the Armenian population within the Ottoman Empire.[4] However, the Rwandan Genocide's impact on the targeted group within its national borders is often cited as one of the highest proportional losses in modern history.