Table:
continent	structure	height	year	country

asia	burj khalifa	-	2009	united arab emirates

africa	omega transmitter chabrier	-	1976	rãunion (france)

north america	kvly - tv mast	-	1963	united states

south america	omega tower trelew	-	1971	argentina

europe	warsaw radio mast	-	1974	poland

oceania	vlf transmitter lualualei	-	1972	united states (hawaii)

Look at the table in the image and show any merged cells, specifying their locations with the JSON format of {'top-left':(x, y), 'bottom-right':(m, n)}, where x, y, m and n are indices (starting from 1) of the first row, the first column, the last row and the last column, respectively.

This table does not contain any merged cells.