Coffee 1946: 46.4 gallons per person
Coffee 2005: 24.2 gallons per person
Soft drinks 1947: 10.8 gallons per person
Soft drinks 2005: 51.5 gallons per person
Total caffeinated consumption in 46/47: 57.2 gallons / person
Total caffeinated consumption in 2005: 75.7 gallons / person
The chart seems to indicate tea has stayed relatively flat in the same time period. I'm not sure the history of caffeine pills or ADHD medicine, but those may also contribute to an increased consumption in 2005.
[1] https://www.ers.usda.gov/amber-waves/2007/june/coffee-consum...