user: Question: What is the IUCN for the Cockscomb Basin reserve when the Est. is less than 1998?
Columns: ['Reserve', 'District', 'IUCN', 'Est.', 'Description']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['Aguacaliente', 'Toledo', 'IV', 1998.0, 'Terrestrial.']
SQL:

assistant: SELECT "IUCN" FROM "Table" WHERE "Est." < 1998.0 AND "Reserve" = 'Cockscomb Basin';