Question: When did they start putting security strips in money?
Answer: 1990
Disambiguated annotations:
qaPairs: question: When did they start putting a plastic security strip in US $20 bills?
answer: 1992
question: When did they start putting a metal security strip in US $100 bills?
answer: 1990
question: When did they start putting a security strip in US $5 bills?
answer: November 1994
question: When did they start putting a security strip in US $50 bills?
answer: November 1991
question: When did they start putting a security strip in US $10 bills?
answer: July 1992
question: When did they start putting a "3D security ribbon" in US $100 bills?
answer: October 2013