They gave country specific data towards the end of the piece but I found this from the Irish government:
"A measure of Ireland’s ageing is the “old-age dependency ratio”. This ratio measures the population aged 65 and over as a share of those aged 15–64 and is projected to more than double from 22 per cent in 2020 to 47 per cent in 2050. While the share of older people in Ireland is relatively low today by European standards, the population will age relatively fast so that the dependency ratio will reach the current EU average by the mid-2030s. The ageing process is set to accelerate in the 2030s and 2040s."
" To convert the ratio 2:1 to a percentage, you need to determine what portion of the total population consists of dependents.
In the ratio 2:1, there are two working-age individuals for every one dependent. So, the total number of individuals is 2 (working-age) + 1 (dependent) = 3.
To find the percentage of dependents, you divide the number of dependents (1) by the total number of individuals (3) and then multiply by 100 to get the percentage:
(1/3) * 100 = 33.33%
So, a dependency ratio of 2:1 corresponds to approximately 33.33%."
2:1 would be a dependency ratio of 33%. 47% is almost but not quite 1:1
www.gov.ie