SELECT "Percent of total" FROM table_60536 WHERE "$40,000 to $50,000" = 'n/a'
What's the total percent of the $40-50K ones that have n/a?
CREATE TABLE table_60536 (
    "Data" text,
    "Headcount" real,
    "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
)