In 1700, Charles XII had a standing army of 77,000 men . By 1707 this number had swollen to at least 120,000 despite casualties. Russia was able to mobilize a larger army but could not put all of it into action simultaneously. The Russian mobilization system was ineffective and the expanding nation needed to be defended in many locations. A grand mobilization covering Russia's vast territories would have been unrealistic. Peter I tried to raise his army's morale to Swedish levels. Denmark contributed 20,000 men in their invasion of Holstein-Gottorp and more on other fronts. Poland and Saxony together could mobilize at least 100,000 men.
Question: How many years did it take for Charles XII to substantailly grow his army?
Answer: 7