Passage: Christianity was brought to Iraq in 40's AD/CE by Thomas the Apostle, Thaddaeus of Edessa and his pupils Aggagi and Mari. Thomas and Thaddeus belonged to the twelve Apostles. Iraq's Chaldean minority represents roughly 3% of the population (earlier CIA Factbook), mostly living in Northern Iraq, concentrated in the Ninewa and Dahuk governorates. There are no official statistics, and estimates vary greatly. In 1950 Christians may have numbered 10–12% of the population of 5.0 million. They were 8% or 1.4 in a population of 16.3 million in 1987 and 1.5 million in 2003 of 26 million. Emigration has been high since the 1970s. Since the 2003 Iraq War, Iraqi Christians have been relocated to Syria in significant but unknown numbers. There has been no official census since 2003 the Christian population in Iraq numbers 1.2–2.1 Million.

Question: In which decade did emigration started to be high in Iraq?
1970s