CREATE TABLE table_60536 ("Data" TEXT, "Headcount" FLOAT, "Percent of total" TEXT, "Less than $25 , 000" TEXT, "$25 , 000 to $40 , 000" TEXT, "$40 , 000 to $50 , 000" TEXT, "$50 , 000 to $60 , 000" TEXT, "$60 , 000 to $70 , 000" TEXT, "$70 , 000 to $80 , 000" TEXT, "More than $80 , 000" TEXT, "Mean" TEXT)

What's the total percent of the $40-50K ones that have n/a?
SELECT "Percent of total" FROM table_60536 WHERE "$40,000 to $50,000" = 'n/a'
SELECT "Percent of total" FROM "table_60536" WHERE "$40,000 to $50,000" = 'n/a'