This may be linked to the well-documented shortage of language teachers, with schools warning in recent years that the situation was reaching crisis point.
The challenges they face in recruiting teachers is forcing principals to consider their language offerings. Another factor may be the roll-out of new subjects, including Politics and Society.
The figures are contained in Education Indicators 2020, a snapshot of the education system – from early childhood to third level – at a point in time, while also charting its progress over the previous five years.
According to the data, the proportion of sixth-year boys studying at least one foreign language dropped from 72pc to 67pc between September 2015 and September 2019.
While girls are more likely to take a language, the downward trend was the same, with the proportion studying at least one down from 87pc to 85pc over the period.
On the plus side, the report notes a greater choice of languages, with an increase in the number of schools offering at least two foreign languages.
The report also highlights the large gender gap that persists in the uptake of science, technology, engineering and maths (STEM) subjects for the Leaving Cert, although it has narrowed slightly.
The proportion of sixth-year boys studying STEM subjects remains significantly ahead of girls. In one example, in 2019, 59pc of male Leaving Cert candidates were taking at least two science subjects, as well as maths, compared with 33pc of females. However, while the figure for boys has seen little change over the five-year period, for girls it was up from 30pc.
However, if biology, which is popular with girls, is not included as one of the two science subjects, only 9pc of girls are taking at least two, as well as maths, compared with 40pc of boys.
Among the many other issues covered, the report tracks the slow but steady move to a more multi-denominational school system. At primary level, the proportion of pupils in Catholic-ethos schools has dropped from above 91pc in 2015 to 90pc, while at post-primary level, it’s down from 53pc to 51pc.
Meanwhile, increasing urbanisation has seen a fall, from 46pc to 44pc, in the proportion of small primary schools – those with four teachers or fewer. They now account for 14pc of pupils, down from 16pc five years ago.