According to ELIAS

Glen Perkins 2015Glen Perkins notched his 19th save of the season by pitching a scoreless ninth inning to preserve the Twins’ 6-5 victory over the Blue Jays on the final day of May. Perkins registered 13 saves during May to establish a club record for saves in one calendar month. He matched the highest save total in one month for any pitcher in the last five seasons (Aroldis Chapman in July 2012) and he fell one shy of the single-season major-league record for saves during the month of May (14 by Cincinnati’s Danny Graves in 2004).