Complex sentence: Between 1891-1895, Canary emigration to Puerto Rico was 600, with these being official figures; if illegal or concealed emigration were taken into account, the numbers would be much larger.
Split into simpler sentences: Between 1891-1895, Canary emigration to Puerto Rico was 600. With these being official figures; when illegal or concealed emigration is taken into account, the numbers would be much larger.