Quite the opposite, almost all experts use percentage of GDP as a measure of how much a country is developing its military. Purchasing power and inflation means that $100 billion today is totally different than $100 billion 20 years before or later. Not to mention, the total inflation adjusted amount of wealth in the country has gone up considerably, so even increases in inflation adjusted spending could still mean that the country is dedicating less of it's overall economic output to the military. Percentage of GDP is a much more effective measurement.