The Northern Crusades ran from the twelfth into the fifteenth century as separate campaigns against the Wends, the Prussians, the Livonians and Lithuania, fought by different military orders at different times, and the scholarship studies each campaign on its own rather than totaling losses across the whole span.
What would resolve this A historian's period by period and campaign by campaign casualty accounting across the different Baltic wars, rather than the single figure a shorter, bounded conflict can be given.
OpenCrusading history, Baltic medieval history, historical demography.Christopher Tyerman, God's War: A New History of the Crusades