File:Spain Animated Population Pyramid By Country Of Birth.gif
Source: Instituto Nacional de Estadística https://www.ine.es/dyngs/INEbase/operacion.htm?c=Estadistica_C&cid=1254736176951&menu=resultados&secc=1254736195196&idp=1254735572981
This animation is using the "country of birth data", with all origins besides Spain as "foreign". The data for 90+ isn't availible by single age. The data in tha cart is using the total population for each year, and assumes that the proportion of foreign born is the same throughout the ages 90 to 100+. As the foreign bor poplation is very smal at those ages, any deviation caused by this assumtion will not be visible on the chart.