Fatal Error in export XLS button with 4,298 register in the grid (SC71)

How many registers can I export with the button XLS because the SC7.1 appear the next error.

Thanks in advance.

Eduardo C?zares

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 32768 bytes) in /home/eduardo/public_html/crmtecnologistik/_lib/prod/third/phpexcel/PHPExcel/Writer/Excel5/Worksheet.php on line 248